Boosted GT and Fried Cats

[stannypack]

Correct, if you want to swap them you’ll need one for you factory driver side cat.

I asked them if I could buy one for specifically that and they told me they don’t sell the flanges. You might have better luck.

Couldn't find any flanges that matched how far apart their bolt holes were (4.75" center to center), but was able to find these that should work https://www.amazon.com/PALOZO-Exhau...694-ab4b-f722e041d086&pd_rd_i=B0DCYFYCVS&th=1

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[Robottrainer]

To all of you boosted drivers.

I have a 20 GT vert with a G2 ESS on 93.
I'd like to upgrade or eliminate my cats. Given I enjoy the sound my car has now wondering what you all suggest? I have a Steeda H pipe and Active Exhaust.
I've heard others say eliminating the cats all together doesn't sound good.
Considering performance cats.
I don't have LT headers nor am I convinced I need them as I'm happy with the performance now.
The car is my summer cruiser and I don't track it.

Thanks everyone!

I have posted bits and pieces of what I did for my situation. 2021 Mustang GT PP1 with dealer Roush/Ford Performance supercharger. I never had a cat failure but didnt want to wait around for one.

I first considered the MAK performance kit as they sell it with the Gsport Gensi 2 UHO cats which they say are good for 800Hp forced induction each. I didn't go this route, although I tried. I found them not very responsive. The one guy that seemed to know anything was always too busy to talk to me. Spending 2500 dollars Canadian on something that I couldnt ask questions about was something I did not want to do. Engineermike was more help and he had no skin in the game.

I decided to go 2M Fabricators and bought some Gsport Gensi 2 UHOs from a friend that runs a speed shop locally. The 2M stuff came right away and was reasonable (400 Canadian). The cats were another 1800 Canadian.

Be forewarned...Splicing the cats into the 2M pieces is a lot of work. I made up a fixture to hold the pipes in their stock location. I then cut a rectangular piece of paper the length of the cats and taped it around the pipe. I marked the ends where to cut out a section. The passenger side has a funky hook to the right and there is no real straight section that is longer than the cat so it takes some doing to get it lined up. I ended up cutting it at an angle to get the correct alignment. Sort of...

I started with the passenger side using the drivers side the check for the correct positioning. It turns out the height was correct, but I had about 5-7/16 spacing from the drivers pipe. You need 4 1/2 to work with the oem spaced x/h pipes. So I cut out about a 1/16" wedge close to the cat and bent the pipe inward until I had 4-1/2 inches. Took it to my buddy who did welded it closed (He owns a race shop so he helped we weld the cats in). Then the fun begins...

The driver side header is both easy and hard to get out. You will have to get creative with sockets, and dexterity to undue the 8 lock nuts. Once you get them off, and disconnect the steering column, it falls right out. Some say you can do this with the header installed. I highly doubt it. you will too when you see how much gap you have to beat out of the header outlet. And then weld.

You then have to cut off the Cat. I would cut it closer to the cat as it gives you more room to play with the flange. Use a 40 grit flapper wheel to clean the weld bead off. At this point you will discover that the outlet of the header is oval. The flange is round. You will need to to heat and beat the outlet round to match the the flange outlet.

You could re-install the header, remove the battery ground and the bolt the flange to the new cat inlet, line everything up and tack the flange to the header, and then then weld it. I did not want to run the risk of blowing the PCM or a module to smithereens due to stray current even with the battery disconnected. All these modules are chassis ground.

I re-installed the header temporarily, bolted the flange to the exhaust inlet and then slipped it over the header outlet, used a bunch of jack stands to hold everything. I placed the outlet so it lines up with the passenger side, maked the flange on the header, removed it, tacked it, reinstalled and checked it again. Removed the header again and then took it to get tig welded (the flange is T409 stainless. the pipe and cat is 304).

I re-installed the header permanently (its a lot of twisting and time...fine thread lock nuts. you want be able to get a torque wrench in there either). Installed the new exhaust pipe. Low and behold it was off! too low and and to close the the passenger side outlet. So again, I slit the pipe, bent it outboard and re-welded it. I got more creative to fix the too low problem.

I took a piece of left over pipe, expanded it so it fit over the 3" pile, cut the pipe off, slipped the expanded pipe over the front half and tack welded it to the pipe. Then slipped the back half into the other end of expanded pipe. this let me twist the pipe up and down to make it level with the passenger side. Marked it, took it off and welded the the expanded pipe to the front half. Used a stainless band clamp the hold the back half, much the same way as the OEM one is, less the locating pin.

For the X pipe, I welded the adapters to the x pipe inlet. I had to expand the exhaust pipe outlet slightly to tighten up the fit. Then I used the supplied band clamp to lock it down. Anywhere there was a clamp used I put two slits into the pipe to let it collapse when the clamps are tightened.

Now here I wait until spring... (I cant seem to attache any pictures. I have lots of them)

To all of you boosted drivers.

I have a 20 GT vert with a G2 ESS on 93.
I'd like to upgrade or eliminate my cats. Given I enjoy the sound my car has now wondering what you all suggest? I have a Steeda H pipe and Active Exhaust.
I've heard others say eliminating the cats all together doesn't sound good.
Considering performance cats.
I don't have LT headers nor am I convinced I need them as I'm happy with the performance now.
The car is my summer cruiser and I don't track it.

Thanks everyone!

 

[Robottrainer]

I have posted bits and pieces of what I did for my situation. 2021 Mustang GT PP1 with dealer Roush/Ford Performance supercharger. I never had a cat failure but didnt want to wait around for one.

I first considered the MAK performance kit as they sell it with the Gsport Gensi 2 UHO cats which they say are good for 800Hp forced induction each. I didn't go this route, although I tried. I found them not very responsive. The one guy that seemed to know anything was always too busy to talk to me. Spending 2500 dollars Canadian on something that I couldnt ask questions about was something I did not want to do. Engineermike was more help and he had no skin in the game.

I decided to go 2M Fabricators and bought some Gsport Gensi 2 UHOs from a friend that runs a speed shop locally. The 2M stuff came right away and was reasonable (400 Canadian). The cats were another 1800 Canadian.

Be forewarned...Splicing the cats into the 2M pieces is a lot of work. I made up a fixture to hold the pipes in their stock location. I then cut a rectangular piece of paper the length of the cats and taped it around the pipe. I marked the ends where to cut out a section. The passenger side has a funky hook to the right and there is no real straight section that is longer than the cat so it takes some doing to get it lined up. I ended up cutting it at an angle to get the correct alignment. Sort of...

I started with the passenger side using the drivers side the check for the correct positioning. It turns out the height was correct, but I had about 5-7/16 spacing from the drivers pipe. You need 4 1/2 to work with the oem spaced x/h pipes. So I cut out about a 1/16" wedge close to the cat and bent the pipe inward until I had 4-1/2 inches. Took it to my buddy who did welded it closed (He owns a race shop so he helped we weld the cats in). Then the fun begins...

The driver side header is both easy and hard to get out. You will have to get creative with sockets, and dexterity to undue the 8 lock nuts. Once you get them off, and disconnect the steering column, it falls right out. Some say you can do this with the header installed. I highly doubt it. you will too when you see how much gap you have to beat out of the header outlet. And then weld.

You then have to cut off the Cat. I would cut it closer to the cat as it gives you more room to play with the flange. Use a 40 grit flapper wheel to clean the weld bead off. At this point you will discover that the outlet of the header is oval. The flange is round. You will need to to heat and beat the outlet round to match the the flange outlet.

You could re-install the header, remove the battery ground and the bolt the flange to the new cat inlet, line everything up and tack the flange to the header, and then then weld it. I did not want to run the risk of blowing the PCM or a module to smithereens due to stray current even with the battery disconnected. All these modules are chassis ground.

I re-installed the header temporarily, bolted the flange to the exhaust inlet and then slipped it over the header outlet, used a bunch of jack stands to hold everything. I placed the outlet so it lines up with the passenger side, maked the flange on the header, removed it, tacked it, reinstalled and checked it again. Removed the header again and then took it to get tig welded (the flange is T409 stainless. the pipe and cat is 304).

I re-installed the header permanently (its a lot of twisting and time...fine thread lock nuts. you want be able to get a torque wrench in there either). Installed the new exhaust pipe. Low and behold it was off! too low and and to close the the passenger side outlet. So again, I slit the pipe, bent it outboard and re-welded it. I got more creative to fix the too low problem.

I took a piece of left over pipe, expanded it so it fit over the 3" pile, cut the pipe off, slipped the expanded pipe over the front half and tack welded it to the pipe. Then slipped the back half into the other end of expanded pipe. this let me twist the pipe up and down to make it level with the passenger side. Marked it, took it off and welded the the expanded pipe to the front half. Used a stainless band clamp the hold the back half, much the same way as the OEM one is, less the locating pin.

For the X pipe, I welded the adapters to the x pipe inlet. I had to expand the exhaust pipe outlet slightly to tighten up the fit. Then I used the supplied band clamp to lock it down. Anywhere there was a clamp used I put two slits into the pipe to let it collapse when the clamps are tightened.

Now here I wait until spring... (I cant seem to attache any pictures. I have lots of them)

cats

Couldn't find any flanges that matched how far apart their bolt holes were (4.75" center to center), but was able to find these that should work https://www.amazon.com/PALOZO-Exhau...694-ab4b-f722e041d086&pd_rd_i=B0DCYFYCVS&th=1

Kooks had them

 

[Robottrainer]

I have posted bits and pieces of what I did for my situation. 2021 Mustang GT PP1 with dealer Roush/Ford Performance supercharger. I never had a cat failure but didnt want to wait around for one.

I first considered the MAK performance kit as they sell it with the Gsport Gensi 2 UHO cats which they say are good for 800Hp forced induction each. I didn't go this route, although I tried. I found them not very responsive. The one guy that seemed to know anything was always too busy to talk to me. Spending 2500 dollars Canadian on something that I couldnt ask questions about was something I did not want to do. Engineermike was more help and he had no skin in the game.

I decided to go 2M Fabricators and bought some Gsport Gensi 2 UHOs from a friend that runs a speed shop locally. The 2M stuff came right away and was reasonable (400 Canadian). The cats were another 1800 Canadian.

Be forewarned...Splicing the cats into the 2M pieces is a lot of work. I made up a fixture to hold the pipes in their stock location. I then cut a rectangular piece of paper the length of the cats and taped it around the pipe. I marked the ends where to cut out a section. The passenger side has a funky hook to the right and there is no real straight section that is longer than the cat so it takes some doing to get it lined up. I ended up cutting it at an angle to get the correct alignment. Sort of...

I started with the passenger side using the drivers side the check for the correct positioning. It turns out the height was correct, but I had about 5-7/16 spacing from the drivers pipe. You need 4 1/2 to work with the oem spaced x/h pipes. So I cut out about a 1/16" wedge close to the cat and bent the pipe inward until I had 4-1/2 inches. Took it to my buddy who did welded it closed (He owns a race shop so he helped we weld the cats in). Then the fun begins...

The driver side header is both easy and hard to get out. You will have to get creative with sockets, and dexterity to undue the 8 lock nuts. Once you get them off, and disconnect the steering column, it falls right out. Some say you can do this with the header installed. I highly doubt it. you will too when you see how much gap you have to beat out of the header outlet. And then weld.

You then have to cut off the Cat. I would cut it closer to the cat as it gives you more room to play with the flange. Use a 40 grit flapper wheel to clean the weld bead off. At this point you will discover that the outlet of the header is oval. The flange is round. You will need to to heat and beat the outlet round to match the the flange outlet.

You could re-install the header, remove the battery ground and the bolt the flange to the new cat inlet, line everything up and tack the flange to the header, and then then weld it. I did not want to run the risk of blowing the PCM or a module to smithereens due to stray current even with the battery disconnected. All these modules are chassis ground.

I re-installed the header temporarily, bolted the flange to the exhaust inlet and then slipped it over the header outlet, used a bunch of jack stands to hold everything. I placed the outlet so it lines up with the passenger side, maked the flange on the header, removed it, tacked it, reinstalled and checked it again. Removed the header again and then took it to get tig welded (the flange is T409 stainless. the pipe and cat is 304).

I re-installed the header permanently (its a lot of twisting and time...fine thread lock nuts. you want be able to get a torque wrench in there either). Installed the new exhaust pipe. Low and behold it was off! too low and and to close the the passenger side outlet. So again, I slit the pipe, bent it outboard and re-welded it. I got more creative to fix the too low problem.

I took a piece of left over pipe, expanded it so it fit over the 3" pile, cut the pipe off, slipped the expanded pipe over the front half and tack welded it to the pipe. Then slipped the back half into the other end of expanded pipe. this let me twist the pipe up and down to make it level with the passenger side. Marked it, took it off and welded the the expanded pipe to the front half. Used a stainless band clamp the hold the back half, much the same way as the OEM one is, less the locating pin.

For the X pipe, I welded the adapters to the x pipe inlet. I had to expand the exhaust pipe outlet slightly to tighten up the fit. Then I used the supplied band clamp to lock it down. Anywhere there was a clamp used I put two slits into the pipe to let it collapse when the clamps are tightened.

Now here I wait until spring... (I cant seem to attache any pictures. I have lots of them)

Cats

 

[Robottrainer]

Cats

2M pipes

 

[Robottrainer]

2M pipes

Fixturing and cut locations

 

[Robottrainer]

Fixturing and cut locations

OEM cat cutoff

 

[Robottrainer]

OEM cat cutoff

Header outlet rework

 

[Robottrainer]

Header outlet rework

outlet fit up and weld

 

[Robottrainer]

outlet fit up and weld

Header install and pipe cut off with union and clamp

 

[robvas]

What have you spent so far compared to just buying <whatever brand headers> with the cats in the first place?

With my Kooks I can just swap the mid pipes out whenever I want to go catless or not.

 

[Robottrainer]

What have you spent so far compared to just buying <whatever brand headers> with the cats in the first place?

With my Kooks I can just swap the mid pipes out whenever I want to go catless or not.

Most definitely, however, I would rather do what I did than give someone my hard earned money when they dont have the time of day for me to answer some simple questions, one of which was do you have anything in stock. It was more out or principle that I did all this, not to mention I can do it. You will still need to heat and beat the hell out of header outlet. Cut the cat off, weld on the flange. The only extra I did was weld in the cats to the existing catless kit. If you want to do it right, you still have to pull the header and I can almost guarantee you will still have to do some fitting

 

[robvas]

Most definitely, however, I would rather do what I did than give someone my hard earned money when they dont have the time of day for me to answer some simple questions, one of which was do you have anything in stock. It was more out or principle that I did all this, not to mention I can do it. You will still need to heat and beat the hell out of header outlet. Cut the cat off, weld on the flange. The only extra I did was weld in the cats to the existing catless kit. If you want to do it right, you still have to pull the header and I can almost guarantee you will still have to do some fitting

I wish I could weld so I could do some custom axlebacks, but by the time I bought the equipment I'd be so far in...

But now I know why they charge over $1,000 for an axleback, which is just 2 mufflers, 2 tips, and some piping and a hanger or two...

 

[Robottrainer]

What have you spent so far compared to just buying <whatever brand headers> with the cats in the first place?

Sure if you want to go with actual long tube headers. I didnt. I wanted to retain the OEMs. Headers with UHO cats would have run me an extra 1000 dollars plus having to take a lot more of the car apart to do it. I did headers on a 13 GT500. Not something I want to do again or pay exorbitant fees to have someone else do it for me

 

[robvas]

Sure if you want to go with actual long tube headers. I didnt. I wanted to retain the OEMs. Headers with UHO cats would have run me an extra 1000 dollars plus having to take a lot more of the car apart to do it. I did headers on a 13 GT500. Not something I want to do again or pay exorbitant fees to have someone else do it for me

Oh okay, I thought you had the 2M headers as well. Totally understand headers not being worth it.

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