Well I went back not long ago hoping for a better ET. I built an exhaust for the car from spare parts I had sitting around the shop. I have stock manifolds still and used the stock downtubes until just after the upstream cats. From there on I built a y-pipe out of 2 1/2" pipe going into one 3" pipe with a magnaflow muffler. No resonator, just a muffler....I was surprised at how quiet it actually still is, I suppose that's because it still has 2 stock cats on it.
Anyhow, I managed a 15.12 @ 92.xx (can't remember the mph exactly) with a crappy 2.21 60'. Overall I was shocked how much of a difference the exhaust made....and I'm getting 2 more mpg. I'm sure there's a 14 in it as it sits, not too bad for putting no money into it yet.