Actually, you'll need to be honest and answer a simple question. Will you mod and stay with what you do, or will you mod, then mod, and mod some more?
If you just want to do a lil bit of playing around once or twice... Go with Overkill. Tell em what you are putting in and you're good to go. Might still be worth it if you change things once after.
But if you're going to get the bug and keep changing things, then you'd be better off making an investment in $ & time and tune yourself. LoL
Better than both would be to cut to the front of the line by getting an in-car tune by someone who's been doing it on these engines for a while. : )
good luck & happy trails!
