I installed a Helix bellmouth 3" catless downpipe (INvidia twin but with less polishing), had John at Outback Auto (Auburn, WA) build me a 3" catless midpipe, and got an STI axle-back with 3" flange and had John modify the hangers.
The Helix DP almost fit perfectly with the 4EAT. I had to pry it over a little bit and bolt it down to keep it from hitting the tranny pan, but no rattling so far. This also could be remedied with a small hammer. The O2 bung was perfect, as was the hanger at the bottom of the pipe. This is a great DP, and probably even more perfect with a 5MT.
The car sounds real nice. Even without cats, I can cruise around town without worrying about cops, but when you get on it, it's a bat out of hell.
You can REALLY hear the turbo with this setup. It has more low-end torque and REALLY hauls when you romp on it. Overall, I'm extremely happy with this setup. Highly recommended unless you like to piss everyone off and get exhaust tickets, in which case you're better off with a straight-through axle-back (not dissing big exhausts, I think they're cool in most cases, just not for me).
The whole setup cost me about $370. I bought the downpipe and axle-back used for $140 and $30, respectively.
On to the pictures! It even almost looks stock to the untrained eye (though my 10yr old sister did ask why my exhaust was bigger).
-Andrew
