CoSport found one several years ago but I can't remember who makes it. I want to say Borla but I know that's wrong. Anyway, the cost of a retail CAT-back system is still higher than having one done.
I originally spent $178 on a complete re-do of the entire exhaust from the CAT to the rear and $98 on a FlowMaster. So, about $275 installed.
I JUST re-did the entire thing in January and the same FlowMaster in stainless was still about $100 and the labor and parts at the shop were the same. I added a new stainless CAT ($146) into mine, too, and replaced the flex ($40) pipe and it STILL was less than $500 total.
Find a GOOD exhaust shop. Prefereably, one that is familiar with building exhausts for off-road if you're planning on doing that AND a place that isn't into the insane 'You've got to have a 3.5" exhaust or the world is going to end!!!!!!" stupidity.
You're not running a turbo or a supercharger and a 3.0L/3.5L engine DOES NOT need a 3" exhaust if it's designed correctly. I'll probably get flamed for this, but I wouldn't go ANY higher than 2.5" and 2.25" IMHO is the sweet spot. The last thing you want to do if you're shooting for miliage is to kill your torque in the 600-3000 RPM range - and too big an exhaust will definitly do that. CoSport did a 2.5" just after I'd done my original exhaust and while there was a noticeable improvement on the highway at 3400ish-5000 RPM you could definitely tell there was a torque loss below that. My exhaust, however, did exactly the opposite. There was a very noticeable increase below 3500 and it made NO difference that I could tell one way or the other above that.
I can't speak for other setups other than pipe size like I said above, but I've been VERY happy with FlowMaster 2.25"in/2.25"out. I've been running various models on my '68 Firebird for almost 20 years and the behaviour isn't any difference. One thing you can't argue with those guys - their products have VERY consistant behaviour.
My other sugestion if you're going to have a shop do the work - before you let them loose, get the cost of the muffler that you plan to use and then price it at Summit Racing. They wanted $140 for mine and Summit sells them for less than $100 including shipping. And don't let them hornshawgle you with 'And it's JUST THE SAME as a 'whatever'. It's just a difference brand!!' That's a load of BS. Unless you're talking about straight through glass packs mufflers vary in a lot of ways between manufactures that aren't readily apparent. I've built more than a few exhausts on MUCH bigger engines that required mufflers and you'd be surprised at how much two different brand mufflers that look exactly the same internally can very in performance.
AND, 'cause this'll probably come up next - replacing the CAT probably won't make ANY difference at all in performance or gas milliage. This was argued and evaluated 7-8 years ago and my experience this spring confirms what was determined then. The Mitsu CAT on the Sports is plenty efficient and large enough (flow-wise) for a 3.0L/3.5L. I replaced mine with a new DynaTec screen-type CAT three months or so ago. This thing is barely more than a straight pipe with a piece of very coarse screen across the flow and about as large as a big coffee/soup mug. 2.25"/2.25" placed in the same location as stock. I have noticed absolutely NO difference AT ALL. Except my exhaust is louder. Sigh. No difference in performance in town or on the highway, no apparent change in torque and no difference in gas milliage - bad or good.
The last thing regarding a CAT-back system - You will see a lot bigger improvement over all if you do the CAT-back AND replace the intake air box and filter with something like the Ingen tube and filter assembly or the K&N FIPK with the (modified) Honda Civic/Acura tube from Specter like mine. We've tried both the intake and exhaust seperately and while they both help a little on their own, there was a much bigger difference when combined. IF, however, you plan to off-road your Sport and you need to do water crossings of more than a couple feet you probably should consider some of the alternative solutions posted here over time. My intake sits so high that sucking water isn't a consideration for me. I have more to worry about floating down river at that point. <img src="/forums/images/graemlins/smile.gif" alt="" /> But, open intakes offer NO protection AT ALL, so....
One thing I forgot on my first post until last night. O2 sensors can cause sucky gas milliage and won't necessarily pop a trouble code. They have a limited life span - 80-100K is the sugested change point on some vehicles. O2 sensors degrade over time and the gas milliage will steadily drop. In 400K I've replaced the front twice and the rear three times. The exception was last summer when I replaced both (the front went and I actually DID get a code that time). The only time I've known an O2 sensor was starting to head south was my milliage started to drop below normal and when I hooked up a scanner capable of returning the sensor readings the readings were outside of what Mistu specifies in their service manuals. I replaced the flaky O2 sensor and everything was back to normal.
Make sure you don't have any exhaust leaks, either. ESPECIALLY in front of the first O2 sensor. Any leaks in front of the first O2 sensor will totally jack with your computer and cause incorrect fuel metering. This little 'gotcha' may not pop a trouble code unless the leak is REALLY bad. The flex pipe is the fist place to look, BTW. Stuff a rag loosely in the end of the exhaust pipe to cause back pressure and then listen under the vehicle along the exhaust. It's pretty easy to hear and feel leaks if there are any. Don't blow off tiny leaks in front of the first O2 sensor as inconsequential - VERY small leaks can make a substantial difference.
Make sure you listen up close to the exhaust manifolds, too. The 3.0/3.5L exhaust manifolds have a tendency to crack if they're hot and get splashed with cold water and/or submerged. This, ALSO, won't necessarily pop a trouble code even if they're BOTH dang near split in half. <img src="/forums/images/graemlins/frown.gif" alt="" />
Edward
