would a scion tc or toyota camry exhaust sytem fit?

The entire exhaust system from manifold to tailpipe, from a Camry or Scion to a Matrix? No. Some components may be interchangeable but not swapping the whole thing if that's what you mean.

Yeah, in every Matrix it's a custom fit.

I'll second David. I think Eric's probably referring to just an aftermarket performance axel back system. In that case the answer is still no they won't fit. Even if you got a matrix XRS/ vibe GT exhaust for a base matrix/vibe it still would not fit because the pipe diameters are different between base and XRS/Gt. I found that out the hard way when I bought a Borla exhaust system off a friend who had a Vibe GT. I made it work with modifications and new flanges but it will not bolt directly on. You could get a universal muffler and weld it in place of the stock muffler-that would work just the same.

Will a exaust system off a o9 Toyota Camry fit on a 01 Toyota camry