Go with something already made for the car. Otherwise you'll end up just supplying %70 of the materials for a custom kit which means by the time its over you'll end up spending MUCH more than what you would have on installation of a bolt on kit. Boosted Performance single turbo kits are pretty reasonably priced. Also you can consider a supercharger set-up. It is much more affordable to get a turbo set-up installed than a twin/single turbo set-up. Stillen makes a solid bolt on kit and I think GTM has several to consider.
Thanks,
Alex Goodwin
AlexG@motionlabtuning.com