Cat Back Performance

[tezflow]

Hi Guys,

I just got a r33 gts25t completely stock. An exhaust is the first mod i wanna do so what i was wondering is will a cat back exhaust do much as far as performace goes, or is it mainly just for looks/sound. different ppl have told me different things some reckon cat back will give a bit more power. So what i wanna know is it worth doin, or should I just get a full exhaust system put in right away? Thanks for your help!

[Ronin]

Personally i don't think a cat back does squat in term of performance. It's like putting a fire hose on the end of a garden hose, it don't make the water come out any faster.

[someonestolecc]

Get a full 3" system.

BUT if you can't afford the manifold + dump pipe just yet then I think a high flow cat + cat back would be better than a stock one.

I wouldn't really bother with a cat back if the cat was stock however.

My assumption is based on my belief that while a stock manifold and dump can flow more, the bottleneck for a stock car is the actual cat and mufflers backwards of the cat.

Cheers

[tezflow]

Ok guys thanks for your help

[xRHETTx]

Yes it definately adds performance. A good analogy is trying to suck air/water through a hose. If the hose is short, its pretty easy to do. If its too long, you cant do it at all. So saying that it makes no difference because the front pipe is still restrictive is wrong. Each part you increase the diameter of decreases the pressure drop and therefore increases performance.

I think in HPI they got about 10-15kW from changing to catback and filter on an R34 GTT? Then another 6kW from the front pipe?