I'll pose this one to the masters, I'm totally puzzled. First a little background - 95 Talon w/AIC intake pipe and filter, short throw shifter, APEXI S-AFC, pacesetter header just bolted up to the stock exhaust. Everything ran fine decent speed, great sound. Last week I switched up the entire exhaust, now 2.5" catco cat, custom bent 2.5" aluminum pipe back to some generic shiny stainless steel muffler. When I finally got it on I noticed it coughed and sputtered a little bit at idle but ran fine and seemed to pull a lot harder in the hi range. So I take it to the track and ended up losing almost a half a second in the quarter mile!! I used the apexi and leaned (rich didn't help oddly enough) out the fuel mix and managed to get my times back up to the same as always, but on cold mornings I now noticed at idle its coughing and sputtering like a maniac and I have to let it warm up like a carbed car before I can move...any suggestions?? Thanks in advance!!

Doc

perhaps that generic muffler is clogging up your system with way too much back pressure.. other then that i'm not sure.

may have shit in your exhaust. sounds like you have a clog. take it back and tell them they effed up yer car. other than that all i can think of is maybe your cat is goin bad. but i don't think a bad cat would do that.

Check your O2 sensors.. do you have a CEL?

off subject but the intake you have is "APC" not "AIC" or "A1C" or whatever else people seem to mistake it for. i felt bad enough for having APC parts on my car at one point, it was even worse to hear people say A1C, but an intake is an intake so at least thats all the APC you got on your car. call APC the complete opposite of JDM (or the complete opposite of quality)

I have an Air/Fuel ratio gauge and the blue wire mod done in my S-AFC and the O2 sensors are doing their usual thing and the voltage seems to be right in check at WOT, so I'm gonna look more into the clog since I did have this done by a shop(first thing I let someone else touch, BIG mistake)..when we left the shop my buddy was followin me he said he thought he saw something white fly out of the muffler...makes me think...only one thing is white in exhaust land, catalytic converter honeycomb stuff...so that(I hope not) could be the problem...thanks for the tips guys...now all I need is a nice little camera on a stick so I don't have to tear my exhaust apart x(
oh well...out to the garage I go!

glass packing (in mufflers and resonators) is white in color also (at first) so perhaps the muffler is dorked up inside and some packing got loose and clogged.

easy way to find out.. shove a pole up your exhaust. if it hits anything within a foot or so.. then either it's a low-performance chamber style muffler.. or if you know it's a nice straight threw muffler.. then something is blocking the path that shouldn't be.

Try adjusting your engine timing. A friend of mine put a 2.5" pipe on his Miata and slowed his engine timing down so he got more power all through out the RPM range and not just the High end.

P.S. I still beat him...

Cant adjust the engine timeing on these cars without an aftermarket ignition that allows you to do so...no distributor to adjust, just coil packs.

Couldn't this be a lack of back pressure problem too?? If there isn't enough the engine can't run right, or if there is too much. With a straight through pipe or generic muff I've heard of problems at idle, but better performance at the top.