I was about to go get one today and was wondering if it will make a difference in power??? Will i feel the boost in power? oh, btw i'm also getting a cat-back at the same time. let me know

 

it will be alot louder with a testpipe and full exhust system. you should instantly feel more power (2-5hp)

 

you should see an inprovment in top end for sure- the climb to redline should happen faster

 

Well considering that your doing both at the same time yes you will notice an increase in power now if you already had a cat back and you added a test pipe I think it would add very little but not enough for you to notice. I would assume that it would be the same if you have a stock exhaust and just added a test pipe as well.

 

I think my Si lost power with the test pipe and a non resonated Thermal Exhaust... I went back to the CAT. The car felt like it had zero torque and only made more noise at the top end.

I recommend saving your money.

Now with a turbocharged car.... that is a different story.