Hi,
I have many doubet about WRX 02'

Recently, I am thinking to get Helix up/down pipe(off road only style) with HKS Hi-Power 120mm cat back, and K&N performence air filter, but I am wondering how many HP will be increase?

After I install the HKS cat back I felt my car is even slower than the stock exhaust...does anyone know what's wrong with it?

Thank you guys

 

it is a nice gain when you add the uppipe/downpipe combo with a catback

 

Yes, you went from 2.5 inch piping to 3 inch. The bigger the pipe the more torque you will lose from a nearly stock setup. 3 inch piping only benefits if you have a bigger turbo.

My advice: Get the smallest diameter uppipe available for the wrx. Try a Perrin or Hks uppipe instead of the Helix. Helix uppipe diameter is too big. It's like 2.2 inches or something like that compared to the Perrin's or Hks (which is roughly at like 1.7 to 1.9 inches). Smaller uppipe will decrease your spool time to allow for quicker boost.

2nd: Get a downpipe and catback that has 2.5 inch piping. Don't go for 3" because it's really not needed for a stock turbo setup. This will improve your torque.

 

Thanks a lot~ I'll post again after I put it on~

 

ooooooh....now thats good advice!!! :banana:

 

Hi-Power is not 120mm. Its 75-80mm. 120mm is the muffler size.