[mike100]

One thing I am sure of that if you are worried about losing the resonator due to extra dB's out, you will be horrified with many of the aftermarket systems (including the Corsas- they are just plain loud when you stand on it).
I like Sammy's idea with the 3" turbo mufflers, but I haven't been able to find any dual outlet kind that are smaller in overall length. For now (since i don't have headers) the stock mufflers make about the same power as any other pipe. My restriction is the factory manifold so I will run it the way I have it now.

At some point, I may sell my Corsa cheap (the resonator was welded previously) and the pass side flange is custom so welding may be required to install that.