If I replaced the 2 pre-cats and main cat with just a straight pipe and used my greddy cat back dual exhaust will that give me enough backpressure?

 

umm.......if you have a S5 its will be fine but replacing main cat on a S4, you will have to find other means for the ports. If your still interested.....I will sell you my corksport straightpipe for the main section. I just bought a resinator for the mid-section.

 

what size you plan on using???

 

PM me if interested, its 2.5 inch

 

heres a pic of it

 

I planed on using the bonez straight pipe from rx7.com and im pretty new to the rotary thing so how do i know if its an s4 or an s5

 

 

S5 1989-1991
S4 1986-1988

 

No offense jgrts20 but, why do people spend $75 or more on a straight pipe? It is a 17 inch piece of pipe to replace the main cat, get that and have 2 flanges welded on at straight angles. I got mine welded with pipe price included for $20. The pipe was like $6. Most exhaust shops will do this because they have no clue what your using it for, and you don't need to tell them. You'll probably need some new exhaust gaskets too.

 

bump

 

some states like VERMONT exhaust shops dont do this tpye of work due to emissions...........thats why, any other questions?
(useless your in with someone that can do this work).

chris

 

This can be done by driving the car to the muffler shop with the center section missing and asking them to weld up a "connection" or Test pipe. They will not remove the cats but they will fill in the gap with something without breaking any laws.

 

Well actually the exhaust shop doesn't have to know what you are doing with a 17in piece of pipe with two exhaust flanges on it, and it's not illegal for them to make that piece. Now if you brought your car into them and said, "take my catylitic converter off and weld a straight pipe on that sucker." Then you might run into problems. I live in California, where as you might know emission testing is rigorous, MIDAS did not have a problem welding and selling me the piece of pipe. I didn't; however, tell them what I was using it for.