The first two are eliminated and the third is replaced with a high-flow.

 

eliminate the first two, or first one, depending on year. S4=3 S5=2 (right?) you can gut all three if you retain a stock exhaust.....usually. sometimes the stock exhaust won't produce enough backpressure. so your best bet is to hollow the first two, or get a pipe made, and replace the main cat. with a Bonez high flow cat.

 

so do i have 2 or 3 i have a 91 s5 n/a the one i replace is right before the y pipe right can i get a link for the high flow cat for the rotary engine

 

so do i have 2 or 3 i have a 91 s5 n/a the one i replace is right before the y pipe right can i get a link for the high flow cat for the rotary engine

 

ok ive read all these posts and im still lost hehe. What im going to do is go pass emissions. Then i want to install a rb header and pre-silencer into a straight pipe back to a apexi n1 muffler. Now what im wondering is what eactly do i have to do remove and where do i put the air tub thingy and wtf am i supposed to do with my air control valve and air pump. Should i remove all emissions stuff now while my engine is out of the car? Getting new engine. Will i have to worry about aux 5th and 6th ports? Ok im so lost if anyone has aim my name is Bigdaddyk2004 guys help plse. Thanks,kevin. Oh yeah its a stock motor. Also what about this one, putting a t2 mas into a n/a is this do-able. laterz.

 

ok still need some help. I have a 86 s4 rx7, just got a custom made header. Should i leave the acv on along with the split air pipe and do what gatlin did just weld it into the exhaust pipe, right after the header? I researched the way to make a system on rotary resurrection, as well as running a 12v compressor. All these sound like really good ideas, not for me though. I dont really have alot of automotive experience and I dont think ill be able to make either of these setups. Is it just not worth having a header on a s4 N/A? thanks,kevin.