I'm just going to give my opinion here...what is it you want to accomplish? HP figures are nice, but are you looking to run in the 12s, the 11s, the 10s? All of the comments here are valid, and if I were going to pick an exhaust system, I'd probably go for the Thermal, but actually even a dual 2.25 system like the Borla is still nearly 8" of of total exhaust area. A 3" system is a bit over 7" of area. I can point you to numerous dyno tests on the internet showing engines pumping 750+ hp through a single 3" mandrel exhaust with muffler. That is much more than even the best upgraded turbos are capable of producing on the ST platform currently, so unless you're looking for a lot more, your Borla is probably fine, exhaust-wise.
My point being that if you look at what you're trying to do first, people on this site could give you a better idea of what you need to accomplish it. I can't remember who, but at least one member here is completely stock other than an air filter and a tune and runs in the low 12s (according to their posts). Yep, not as fast as a Trackhawk, but will destroy 99% of anything on the street for about $750 in mods..
