OK. Goto http://solar.innercite.com/comptech/exhaust1.html and see 'Muffler, Power Pro - S/S Axle Back, 3.5" tip (GSR, RS, GS, LS 94-01, 2 door)' for $329.00 for just the muffler, then get the midpipe from
http://www.streetbeatcustoms.com/tucms310.html only if its a GS, RS or LS.
But for GSR see http://www.streetbeatcustoms.com/tucms305.html for $129.95 totaling $458.95 +tax/sh and you can say you have a comptech exhaust system, because you kinda will. Note: the midpipe replacement will cause the most amout of volume increase, but if your not running a GSR I would not worry about it.
This is what I run in my GSR. I now have more torque/power and its not toooo loud. You will set off sensitive alarms if you rev up the engine a little. This is because of the low frequency of the system with the larger mid-pipe.
Also see about getting the Quiet Tip Insert from comptech site because this will be a louder system then stock and the quiet tip helps if you live in a quiet neighborhood.
I love the low rumble I get from mine. The midpipe won't hookup perfectly to the muffler so you will need to use the gasket from the stock muffler to get a better fit.
Also it does NOT give off that annoying fart/airplane noise that you can hear miles away. The only thing on ordering is that StreatBeatonline sometimes drop ships and I guess it can take a while to get the mid-pipe...so order it first! Mine took 2 months to get!