Hey guys just a quick question,

Ive read that the Js give great midrange power gain and some at top but when I read this the car has been paired with aftermarket exhaust, I wonder what the case will be if it is to be paired with the stock exhaust and stock cat? (I have a test pipe but is not installed)

I cant sleep thinking about this

I just dont want to blow all that cash for nothing, this is scary!

 

No header is going to give you large gains with the stock exhaust still attached. You'll still get some gains, but not as much as you could. If you intend to get an aftermarket exhaust at a later point in time, then there's no reason not to go ahead and get the header.

As far as the cat goes, the stock cat does flow very well. You'll only loose a few hp at peak by keeping the stock cat.

 

you wont gain much but with a 70mm single you will gain some power

 

I have the J's header with a stock exhaust and stock cat (which I plan to replace in the future). The gains are mostly midrange. It doesn't push you back in your seat, but it is noticable and you will feel it when compared to stock. If I had to give an estimation.. It added about 4-5 hp midrange and maybe 1-2 top hp. This is of course because I'm still running stock cat and exhaust.