Exhaust Pressure Testing

[Exploded_Muffin]

Hey Muffin, check out the Borla S-type with the 2.5" 60661 resonator. It's actually a very civilized system even without the big restriction (cats) and because it is dual 3" (besides the resonator) it flows so much better than the previous Magnaflow resonated X. When I removed it to install the new exhaust the body of the resonated x was heat checked, so much so that you could see where the exhaust gases were merging from the outside of the shell. That tells me that it was a huge restriction and that it was generating a lot of heat once I added the SC. I had it on my car from when it was NA and it never looked like that before I added boost.

On a side note, how are you liking the return style fuel system and e85? I've been mixing 1 gallon of xylene to 10 gallons of 93 pump gas to act as an octane booster since it has been so hot here in H-town lately. It raises the octane to 95 and keeps me from experiencing positive knock with the 115mm pulley and 100° charge temps.

Funny this is I still have the 60661 resonator which I took off and replaced with the Magnaflow tru-x.
Just a preference but I didn't really like how the 60661's sounded with my exhaust setup.
I only have the active S-type mufflers as the full active cat-back was back-ordered for months when I wanted to get one so got the mufflers instead and paired with the 60661 and custom 2.75 piping.
Might be why it just didn't sound exactly right for me.

The tru-x's gave me a cleaner sound and were quieter than the 60661's but they come with the darned restriction trade-off.

I'm stuck for now but will keep fishing for a non-restrictive setup with a tone and volume I like.
I've been trying to avoid it but I might have to change my S-types for something quieter to get any less restrictive setup to work for me. Thanks for the info

I'll send you a PM on my fuel system so I don't derail the thread

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[TEXAS HEAT]

Funny this is I still have the 60661 resonator which I took off and replaced with the Magnaflow tru-x.
Just a preference but I didn't really like how the 60661's sounded with my exhaust setup.
I only have the active S-type mufflers as the full active cat-back was back-ordered for months when I wanted to get one so got the mufflers instead and paired with the 60661 and custom 2.75 piping.
Might be why it just didn't sound exactly right for me.

The tru-x's gave me a cleaner sound and were quieter than the 60661's but they come with the darned restriction trade-off.

I'm stuck for now but will keep fishing for a non-restrictive setup with a tone and volume I like.
I've been trying to avoid it but I might have to change my S-types for something quieter to get any less restrictive setup to work for me. Thanks for the info

I'll send you a PM on my fuel system so I don't derail the thread

Thanks

 

[K4fxd]

https://duvasanitary.com/product/butt-weld-eccentric-reducer/

Did you take a wiz wheel and cut off the cap on the cat?

How much did this reduce pressure through the cat?

Last, can it be done on the car?

I'd like to just dump the cats but my extended warranty requires all emmissions to be installed and working.

 

[GregO]

https://duvasanitary.com/product/butt-weld-eccentric-reducer/

Excellent pricing. Thanks for the link Mike.
Most fittings are coming from a few mfg. in China as blanks and Laser Etching company names on the fittings. All the fitting quality is about the same until you get into BPE fittings and not many exhaust systems can justify the cost of BPE fittings.

 

[Mach9310]

Funny this is I still have the 60661 resonator which I took off and replaced with the Magnaflow tru-x.
Just a preference but I didn't really like how the 60661's sounded with my exhaust setup.
I only have the active S-type mufflers as the full active cat-back was back-ordered for months when I wanted to get one so got the mufflers instead and paired with the 60661 and custom 2.75 piping.
Might be why it just didn't sound exactly right for me.

The tru-x's gave me a cleaner sound and were quieter than the 60661's but they come with the darned restriction trade-off.

I'm stuck for now but will keep fishing for a non-restrictive setup with a tone and volume I like.
I've been trying to avoid it but I might have to change my S-types for something quieter to get any less restrictive setup to work for me. Thanks for the info

I'll send you a PM on my fuel system so I don't derail the thread

I’m going from tru x to the 60661 resonator. With no mufflers would it even be worth running it as opposed to running turndowns directly from the headers? I’m trying to get the most power from the exhaust while not being too loud. The best sounding option will of course be the 3” S type active catback with the 60661 but that’s $2700 that I’d like to avoid spending.

 

[Exploded_Muffin]

I’m going from tru x to the 60661 resonator. With no mufflers would it even be worth running it as opposed to running turndowns directly from the headers? I’m trying to get the most power from the exhaust while not being too loud. The best sounding option will of course be the 3” S type active catback with the 60661 but that’s $2700 that I’d like to avoid spending.

Is your car a daily driver or strictly a track car?

For a track car just go with turndowns directly from the headers, cheapest option with the most flow.

For a daily driver it gets more complicated and depends on your sound tolerance.
I'd get the 60661 with the 2.5 connect modification similar to what @TEXAS HEAT mentioned a few posts back. Will flow better and only be slightly louder than the tru-x.
It's a cheap enough experiment and you always have the option of adding the S-type cat-back to the 60661 without any redundancy in the parts you'd have already purchased

 

[Mach9310]

Is your car a daily driver or strictly a track car?

For a track car just go with turndowns directly from the headers, cheapest option with the most flow.

For a daily driver it gets more complicated and depends on your sound tolerance.
I'd get the 60661 with the 2.5 connect modification similar to what @TEXAS HEAT mentioned a few posts back. Will flow better and only be slightly louder than the tru-x.
It's a cheap enough experiment and you always have the option of adding the S-type cat-back to the 60661 without any redundancy in the parts you'd have already purchased

It’s a weekend car but it’s street driven 99% of the time. Hopefully the 60661 with turndowns immediately after the resonator is at least tolerable as far as loudness goes.

 

[Proshop]

I would love a sound clip when done. I want a cat back but cant decide on a system. Right now its between a corsa double H but add a resonator (two bottles or the one your using), magnaflow xmod though i wish it was a h pipe resonator and 304 throughout, or stock gt500. I have things i like and dislike on everything i see on the market....

My shop sent this to me earlier as a teaser. I’ll try to get more in the next few days.

 

[smokescreens]

My shop sent this to me earlier as a teaser. I’ll try to get more in the next few days.

That sounds great to me! Thats the borla atak active and dual in dual out resonator right?

And i forget if you have longtubes or are catless. So many exhaust videos

 

[FruityJudy]

So is the 60661 or the stainless bros res louder? I have the Xmod system. Catless, 2.5 connectors at the moment, tru -x resonator, then rest of the exhaust

 

[Exploded_Muffin]

So is the 60661 or the stainless bros res louder? I have the Xmod system. Catless, 2.5 connectors at the moment, tru -x resonator, then rest of the exhaust

My stainless bros were significantly louder than my 60661s. You mileage may vary...

 

[FruityJudy]

My stainless bros were significantly louder than my 60661s. You mileage may vary...

And in comparison to the tru x?

 

[K4fxd]

If I read the graph correctly you lost 5 psi of back pressure by using the 4x3 on the cat along with getting rid of the 2.5 inch pipe.

At what mass flow rate is this?

 

[engineermike]

Did you take a wiz wheel and cut off the cap on the cat?

How much did this reduce pressure through the cat?

Last, can it be done on the car?

I'd like to just dump the cats but my extended warranty requires all emmissions to be installed and working.

The first time, I cut the cat using a band saw then cleaned up the hole with a bur bit. The second time I used a cutoff wheel to cut the prior weld. You have to fit up the reducer at the desired angle then mark it and cut it. Can’t be done on the car; at least not by me. In fact, it requires several iterations…cut small pipe off, install cat, fit up reducer and mark cat, remove cat, cut factory reducer, install cat, tack on 4x3 reducer, remove cat, weld out reducer, install cat. However, on these cars, pulling either cat and re-installing is super easy. The hardest part is getting the driver’s side of the car high enough.

 

[engineermike]

If I read the graph correctly you lost 5 psi of back pressure by using the 4x3 on the cat along with getting rid of the 2.5 inch pipe.

At what mass flow rate is this?

The last test data was on a Whipple and 3.375 pulley, about 15 psi boost and well over 90 lb/min flow. 1.8-1.9 load at 7400 rpm.

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