Ok I'm looking to replace the factory stainless muffler on my 89' STS with a performance stainless steel model. I assume I'm going to have to go with a universal muffler.

When I measure the dimensions do I measure to the outside of the rolled edge or the inside? Anyway here's what I have.

The expanded inlet is 2.5" ID and the outlet is 2" ID. The configuration is offset to offset and the length inside the rolled edge is 19.75" the height is 5" and the width is 9.25"

Does anyone have any resources.

RSM RACING has:

RSM Stainless Steel High Flow emissions legal cat back exhaust system. Includes 2.5" or 3"SS custom pipe, 304 SS polished mufflers and 4 SS polished resonated tips, 3" high flow cat optional for $250.00. 12-14 HP gain and exclusive sound.

See their ad on the right side of this page for contact info. Be sure to let them know you found them from LVC...

did you look into the RSM system?

I always advise having a performance muffler welded into the system rather than clamped. For that reason, I'd suggest a muffler shop like Midas, Mufflex, or Mienike Muffler. They actually do offer good performance mufflers at competitive prices.