T Byrne Motorsports has them for 93-95 and 96 on up but nothing for 3rd gens.

I got an automated responce from Mufflex on where to buy but it only was a verification of received email.

Is there any install issues with the 4" vs the 3.5"?

 

Thunder Racing has them. My factory system scraped some speed bumps then when I installed the 3.5" Mufflex it contacts even more. I want to try to tuck the system up tighter. I can't imagine the 4" on the car. Do you really need to support that much exhaust flow. I think the 3.5" is plenty especially when compared to the 2.75" factory set up. Installation was sweet but it helps if you can weld. You want to weld the tips on as well as the hangers, clamps work but look cheesy.

 

I would think a 3.5" should support just about anything n/a. But if you want to go with forced induction, a 4" system wouldn't hurt at all! Even on a healthy 350 it wouldn't hurt, or so people with them claim! Why can't you order if from them? Their site goes into pretty decent detail about their systems. A little expensive too from what i can tell. Too bad Summit or Jegs can't pick them up and support a decent discount! lol

 

I went directly through Mufflex for mine, but I would dial-in a place like Thunder Racing and use their discounts if I had it to do over . I know I just got a card in the mail for 10% off through the holiday season at Thunder . Plus, places like that always have deals going on that should save you some coin.

As for the size, just get the 4" and be done with it FOREVER. the 4" fits fine and the only difference is since it is fatter it hangs down slightly more where it can't be tucked up into the trans tunnel towards the rear of the car. The front part can be tucked up real nice but towards the rear it kind of hangs down because it has to be routed slightly to the passenger side of the tunnel area since there has to be clearance for the driveshaft to move up and down. This is where a 2.75" or even 3" system has no issues at all and tucks all the way up into the tunnel. You do have to pay attention when installing any catback to make sure you get it installed with as much ground clearance as possible. You can really drop the clearance to a minimum if you aren't paying attention to how it all lines up when you do the final tightening.

All in all I wouldn't hesitate to go with the 4" again, and again, and again.... . I just cannot imagine how you can possibly have TOO MUCH flow when referring to the catback. People claiming you don't need a 4" never seem to have any numbers to back it up. Not that I have a lot to go the other way, but I have witnessed PLENTY of cars make more power and/or go faster open headered that are running even true dual 3" systems, so..... Ideal would be true duals with an X but we all know how fun that is to make for these cars .

With the 4" I just avoid speed bumps completely and have no problems. Not a big deal as my SFC system makes speedbumps a thing of the past anyways.... If you need to be able to go over things like speedbumps you better stick to a 3" at the largest.

my $.02

 

I have the 3-1/2" Mufflex system on my Camaro - did it when I swapped to a 12 bolt rear. It scraped like a mother as I did it myself (only using clamps). I took it to Mufflex and they cut one pipe, aligned it welded it in place and bingo, not a problem at all. I'm sure a 4" would fit no problem (and my y-pipe sits extra low too).

I would only go for a 4" if I had a big ci motor (383 or larger) or had a power adder (supercharger or nitrous).

 

You can get the 4 inch system to fit really tight. I have mine so close that you cannot even tell the system is 4 inches until you get under it. Hell, my TCI trans pan sits lower than my exhuast does. If you do go with the either system, just don't use the freakin clamps. Just take it to a shop and get it welded on. It will save you time, money, and the frustration that the clamps(bands) will cause.

Have fun.