stock cat to high flow

[svtfever]

anyone welded in high flow cats or done a cat delete on their stock headers? any increased exhaust flow and exhaust volume, noise from this.

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[El_Centenario]

I have. They do have a noticeable gain in acceleration and sound. Cold starts are LOUD but once up to temps it has a nice rumble to it. WOT runs are sound great with my set up. I did notice some drone at hwy speeds when going up hills. Normal hwy cruise is close to non cat delete. Exhaust fumes are noticeable when running gas, but not quite as much when on e85. Haven't raced the car at the track with cat deletes and e85, but I'm sure there are some solid gains! You wont be disappointing.

 

[RoyalGuard]

Link to the high flow cats?
200 cell?

 

[svtfever]

did you have to retune

 

[Lonmon]

I have the stock manifolds, mak cat delete pipes and 3" magnaflow highflow cats welded in to an MBRP street h-pipe catback. I lost 1hp with the high flow cats. Sound was only slightly milder with the cats. I think you will need a tune to shut off the rear o2 sensors due to the low cell count of the high flow cats. The cats will reduce fuel smell. My exhaust is not too loud with the MBRP street but I had a Stainless Works catback before and it was race car loud! I could not live with it, not bad if you baby it but hella loud if you were on it at all. Wake the dead at cold start. Haha

 

[svtfever]

why would this cause you to loose power

 

[beefcake]

high flow cats are just about as loud as full headers.. not a ton of change in exhaust tone

 

[svtfever]

but car will be louder, right?

 

[beefcake]

but car will be louder, right?

car will be louder,

 

[svtfever]

nice

 

[Lonmon]

why would this cause you to loose power

Sorry, I should have explained better. I had the cat delete pipes with no cats and it was too loud with the SW catback. My first attempt to quiet things down a bit was the high flow cats. I lost 1hp from my dyno with no cats at all. Basically no real difference really. The high flow cats did not make much sound difference and I had to try a different catback. The MBRP street did the trick in reducing the noise enough to be tolerable with no drone. Hope this clears up any confusion.

 

[svtfever]

oh thanks, I want my borla ataks a lil louder

 

[RoyalGuard]

Got a link to the catalytic converters you bought?

 

[kai20035]

high flow cats are just about as loud as full headers.. not a ton of change in exhaust tone

Sorry to have reawaken this thread and hope to get some help! I also have the MAK race pipes but with the Borla S-Type & X pipe setup. YES, to me it was too loud for my taste so went back to original Borla S-Type & X pipe setup and had the MAK race pipes removed! What I was thinking of doing was going with the Magnaflow 54959 with 400CEL instead of the 200CEL you had on your high flow cats which should give you some noise but nothing close to your 200CEL HFC and have them welded to my MAK race pipes to decrease the volume and figured 400CEL was the best or safer gamble to take to avoid having an obnoxiously loud exhaust note! I'm not worried about drone because all Borla exhaust eliminate all drones but my tone was just too loud and just want it reduced by 50%. I figured since the S550's have a CEL of 700 on the stock cats by welding on the Magnaflow's with 400CEL would be the safest gamble for this last attempt in getting some bang without the huge BOOM! From what I've been reading the higher CEL count will reduce more exhaust noise without losing your original exhaust tone! My Borla S-Type sounds great even with the MAK race pipes but it's just too damn loud for my taste...

 

[GregO]

What I was thinking of doing was going with the Magnaflow 54959 with 400CEL instead of the 200CEL you had on your high flow cats which should give you some noise but nothing close to your 200CEL HFC and have them welded to my MAK race pipes to decrease the volume and figured 400CEL was the best or safer gamble to take

Just something to think over.
The Cats you mentioned are a failure waiting to happen. If you’re set on going down the road of metal substrate high flows cats be sure what you use has a furnace brazed core, mantled if you can afford it.
I’ve seen far to many substandard cats unwind and melt to the point of horrible engine damaging back pressure.
For starters take a look at the link below. There are only a few other High flows that I’d suggest.
https://www.stainlessbros.com/Catalytic-Converter_c_84.html

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