2.5" vs 3" cat back exhaust 03 Cobra

AftrBurNr · Oct 18, 2007

just wondering which is better, someone told me that 3.0" only benefits a cobra that is around 600 RWHP, but thats where i wanna be anyway..

and till then i was planning on running with a magnaflow x pipe with high flow cats, so wont that make up for the lost back pressure?

I figure 2.5 highflow cats + 3" cat back is like the same as not having cats and a full 2.5 system.. am i wrong?

all opinions appreciated

thomas91169 · Oct 18, 2007

i would go into detail on why a 3" will not matter.

point is, it really wont make any difference until a 2.5" becomes a hindrance, which like stated, is pretty far from stock.

VR4 · Oct 18, 2007

unless you plan on going twin screw, whipple, or turbo...stay 2.5"

Gearbanger 101 · Oct 18, 2007

The only thing a 3" exhaust is going to give you at this point is a slightly deeper exhaust tone. That's a lot of money to spend for just that.

AftrBurNr · Oct 18, 2007

Gearbanger 101 said:
The only thing a 3" exhaust is going to give you at this point is a slightly deeper exhaust tone. That's a lot of money to spend for just that.

Its the same price... deeper is good

and i guess what i really wanna know is if its bad for the car.. should of made that clear

Uncle Meat · Oct 18, 2007

AftrBurNr said:
Its the same price... deeper is good

and i guess what i really wanna know is if its bad for the car.. should of made that clear

No, won't be bad for the car. Just won't be as beneficial as far as power gains are concerned, at least not until you are making big numbers and pushin' lots of boost.

U.M.

Gearbanger 101 · Oct 18, 2007

Well, on a N/A car, it would normally cost you a little off idle and bottom end torque....and with normal driving, it still might. But with the Eaton on there, you won't notice it much, if at all when you're into it.

Since they're the same price, I'd say go right ahead and order the 3".

VR4 · Oct 18, 2007

wont be bad for the car. just compromise ground clearance and make everything tighter under there.

SVT98Snake · Oct 18, 2007

I gained a little(5-7 hp) with mine...I love it though.

yomadmike · Oct 18, 2007

I'm running 3". The speed shop said 2.5" is fine for my car but if I ever turbo or s/c my car it would make my car sound like a Chevy truck with glass packs. I went with the 3", and don't regret it at all.

SVT98Snake · Oct 20, 2007

yomadmike said:
I'm running 3". The speed shop said 2.5" is fine for my car but if I ever turbo or s/c my car it would make my car sound like a Chevy truck with glass packs. I went with the 3", and don't regret it at all.

With a 99-01?

Did you lose a lot of TQ?

Not slamming, just curious. My buddy had a 99 and put a 3" flowmaster cat back on and lost torque and his ET went from 13.40's to 13.50's.

yomadmike · Oct 20, 2007

SVT98Snake said:
With a 99-01?

Did you lose a lot of TQ?

Not slamming, just curious. My buddy had a 99 and put a 3" flowmaster cat back on and lost torque and his ET went from 13.40's to 13.50's.

As far as what I noticed, I didn't loose any. But my car is set up for autocross so it doesn't see the drag strip. Last dyno was 316rwhp, 301lb/tq. So usually you get more torque than hp but I also have an aluminum flywheel which doesn't help torque either but autocross is a whole different world as far as setting up your car. And everyone knows the 99 IRS isn't ideal for drag racing. lol

2.5" vs 3" cat back exhaust 03 Cobra

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