which cat and muffler

[turbottt1]

we have a 91 shelby and need to update the exhaust. Some ideas on which cat. convertor , muffler and size of tubing. We do have to pass ohio emmisions. If it matters the car is a auto. thanks for all ideas and help. steve

3" exhaust, 3" catco cat, 3" straight through muffler. muffler choice depends on how loud you want it. no matter what get a straight through muffler, no flowmaster style mufflers.

[Aries_Turbo]

I assume its a mitsu turbo and a 2.5l t1. do you have factory engine management with no extra provisions for extra fuel. i ask this cause with the mitsu turbo you wont be able to control the boost with the above mentioned system and either the factory boost control or a grainger. itll spike too fast and hit overboost shutdown all the time at WOT. now if you have a setup with additional fueling above 15psi and an intercooler then go for the 3". if not you might need something a little smaller.

Brian

[turbottt1]

thanks for info. We do have stock setup. Not looking for a rocket burner just a nice gain in performance. Would a 2.5" setup work. steve

[Aries_Turbo]

from what i hear, a 2.5" with a highflow cat and muffler should work. on some mitsu setups the downpipe is 2.5" already. if so, all you need is the catback pipes and a high flow cat and a muffler. with no intercooler and the mitsu i wouldnt recommend going above 12psi with a grainger valve. if you get a cooler you can go to ~15. seriously though a few cheap mods will allow you to run 15 lbs and a 3" exhaust and will provide safegaurds against spiking though from how you are sounding it looks like you dont need it.... but if the bug bites! youll want it later.

an intercooler (go digging around in the junkyards)
a map cutout zener diode mod (www.thedodgegarage.com)
a napa hobbs pressure switch and a junkyard extra injector (www.gusmahon.org)

those things will allow you to run ~15-18 psi (if all your fuel system is in proper working order) and the car will be much faster. but its all in what you really want or need. good luck

Brian

[turbottt1]

thanks for the info. Sounds like a plan to me. We really don't need it, but if your going to have the nicest looking shelby in town you better have something to back it up with. steve