I've got a modified intake and am planning on getting a K&N filter. Then i'm goin to attach a HKS downpipe to my ApexiN1 akleback and have someone replace the uppipe and header with GtSpec. how many whp can i expect with this setup? Has NE1 had problems with a setup like this, like CELs or running lean?

 

Can't tell you what the wheel horsepower will be, but you will get a CEL without cats, at least in the downpipe.

 

i thought if i replaced them all and the car can breath it wont go on. i've also heard stories of people putting in Downpipes and gettin cels but after replacing uppipe it goes off. i'll be opening everything up including the header so....whacha think?