If you're in Houston, I'd say check out Late Model Racecraft. They're always coming out with ridiculous cars and I hear nothing but great things about them.
Also, fwiw, you'd probably get a lot more responses in the Texas section on LS1tech.com, lol.
theres this guy named shaner that i heard does wonders when it comes to tunes..you would have to go check out ls1tech and try n dig up more info on him.