I don't know wether to get 2.5 inch piping or 3 inch piping. People have said i'll loose power if i get 3 inches. but i wanted to ask you guys since hopefully you guys know. i have 2 1/4 inchs right now cuz the guy ****ed up. so let me know. thanks.

 

since your profile says wrx, i'd have to say 3" is definitely my vote. always good to have minimal backpressure when dealing with the exhaust downstream of the turbo.

 

would 3 inches make it louder as well?

 

yes

 

how much HP are you looking for?

 

if u plan to keep the stock turbo, 2.5 inch piping is good enough. You will get more low end torque from 2.5 inch piping. You will get more top end from 3 inch piping. That being said, it's really all about preference. However, there aren't many companies who make full 2.5 inch pipes since 3 inch is more popular. But if u plan to upgrade the turbo in the future, it's best to get the 3 inch instead.

 

In a turbocharged vehicle, the less exhaust system backpressure there is after the turbo, the more power it will produce generally across the entire rpm range if engine management is properly tuned for any modifications. The turbocharger should be the point of greatest restriction due to sizing and power needs, not the exhaust system diameter.

Tuned-length and diameter exhaust systems have their place from the cylinder head exhaust ports leading up to the turbo, to keep velocity sufficiently high at lower engine speeds while maintaining enough cross sectional area to feed the engine at maximum rpm and power - it's usually a compromise.

2.25" diameter tubing is too small for performance use. 3" tubing is what you want for a mildly modified WRX, all the way from the downpipe to the muffler tailpipe. Choose an exhaust that is as close to a straight shot to the muffler as possible and any necessary changes in direction should not be abrupt 90° bends which are extremely restrictive.

 

i was reading in an import tuner that on the wrx the 3 inch cat back really doesn't do much. most of the power comes for catless downpipes. i would go with 3 inch tho. i've got the 3 inch high power exhaust on my 02 and i like the sound and power

 

Alright....I'm a little confused lol. 3" is better for high end torque...correct? Does that mean I'll have turbo lag when it comes to my low end power? I know a muffler shop over here in San Jose where they do custom piping. He's the guy that put on my 2.25 the first time. That fu*ker. I told him 2.5 in the first place and he put 2.25 saying its the same thing, then after that, he wouldn't change it with out me paying him all over again for labor.

 

No, with 3 inch, u will lose low end torque. 3 inch gives you more top end peak horsepower.

2.5 inch u will increase your low end torque. 2.5 inch gives you more low end torque and less peak horsepower up top.

 

Alright sounds good. Thanks guys. I think I'm just gonna go with the 2.5 inches. Most of the races i do are in the city so i rarely hit over 100mph.

Also one more thing...which downpipe would you guys recommend. HKS or Invidia. I'm trying to get one of the two.

 

Which catless downpipe would you guys recommend. HKS or Invidia. I'm trying to get one of the two.

 

crucial racing

 

Is that a brand name?

 

Perrin