Ok, sorry to be jumping into this so late but I've been busy ice racing.
Thought you might want to see this, this is where you want to start so that as you keep going, you'll keep getting closer and closer to factory. The advantage to that is less experimentation and risk. The thing is already set up for you application and clocking and exhaust setup. Anyway what you're looking at here if you don't already know is the/a new, factory fresh Borg/Warner unit that comes on the 2.0 LNF for the Cobalt SS, the Sky Redline, Solstice etc. This is the real deal, not ching chong meow. I happen to know the stealership list price for these is $1,350...and you have to wait a month at that. click to enlarge the pics, I can send you other pics if you need them. pm me for a price;

 

Busa: Hey Yes it will hit the firewall without modification. But we have purposely cut the flange and made it so it would clear the firewall. The picture is before we done all the cutting and fitting.

 

did you give up on this?

 

Yea cuz im going with a v8 and that manifold will work on your build. It is cut to the bottom so it will fit.