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1991S13 »
https://forums.nicoclub.com/1991s13-u22320.html
Mon Aug 22, 2005 5:51 pm
This question has been extensively covered on this forum numerous times - click the SEARCH button in the upper right corner of the window and search for what you are looking for. You will most likely always answer your own questions that way.
It really depends on what you are planning for your car. The most popular catback systems are probably BRM and Apexi, so look into those. A lot of people (including myself) have their own exhaust custom made using anywhere from 2.25 - 3" tubing. Mine is 2.25" stainless I had mandrel bent eliminating as many bends as possible. This was pretty cheap too - the most expensive parts were the header and new catalytic converter. Of course you don't need to replace those, so finding some tubing and a muffler can be done for fairly cheap.
People will argue all day about what the best size is. Some say bigger is best, but others say keep it small. Backpressure is never good, but don't go throwing a huge pipe on expecting to see good gains. A 2.4L engine doesn't push THAT much air. You want tubing big enough to reduce backpressure, but using tube too big will mess with the exhaust velocity, thus increasing backpressure. I have heard of someone gaining 16hp using 3" tubing. If you plan on going turbo in the future, 3" is probably your best choice.