To get to 375hp, it's going to cost you a bit of money. Much easier in a "newer" next gen, motor like a 2012 ATS, Camaro or Regal. So, if you want 375-400hp, here's what you'll need:
1. New aftermarket intercooler (DDM, Werks, Hahn)
2. IC piping
3. High-Flow Cat
To make sure that the 375 is attainable, a new exhaust from Solo (recommended)
?4.LDK head (if you aren't changing turbo)
Then a good dyno tuner. You should see 370 very easy with above....I'm at about 335hp without the AM IC or HFC or LDK head.
?4.5 - The other option is to do the first 3 then add a new aftermarket turbo, but you could see lag depending on the turbo you choose.
And it's all going to depend on who responds here. Many will say something that will contradict what someone else says and so on. Stick to the basics...its going to cost you the same amount no matter which way you chose to go! But the first 3 and a good tuner are definite musts to achieve your goal.
And then there is the meth kit....it depends on the way you want to take your car. Daily reliable driver, or weekend garage queen that you don't mind having issues with once in while...
If you have a factory tune, no matter what you do to your motor, it will always relearn to 260hp. So a tune is MAJOR key in your goal.
Solo Street Race exhaust
ASAP T2 stripes and badging
Windrestrictor V2 lighted in white
Windrestrictor lighted door sills lighted in white
DDM Works IC Piping
Undercar LEDs in white to match Windrestrictor
ZZPerformance dyno tuned - 286HP, 317ft/lbs of torque at 23psi of boost.