Originally Posted by xilli
Basically, the test pipes remove the primary 400cell cats which are the major restrictive factor in the system. You will find if you look at dyno results between an aftermarket HFC X-Pipe and a standard pipe with the primaries removed there is a slight difference in power, but many (including myself) will argue the extra amount isn't worth the $2000+ extra price tag.
I have coupled a Gintani race rear with the x-pipes, RPI scoops, BMC filter and an Evolve stage 2 tune on 98ron and the car feels absolutely amazing! It's almost like jumping into a different car, it's far more exciting and thrilling to drive hard.
This is obviously just my opinion, i'd much rather save the 2k and put it towards an ESS S/C Kit then drop it on a new length of pipe which you already have that does a perfectly fine job.
Sounds mean! i assume you have never used the turner test pipes though? thanks for all the input btw!