Well first off, I'd say get rid of the U-Bend and get a DP and 180* T-Stat before a PCM. Plus with that 3.4" you might have a bit of knock.
AFTERWARDS THOUGH...I'd say grab a DHP. Best Mail-Order Tune Hands Down. Here is the link to 3800 Performance as PFYC no longer carries it...
PCM for Grand Prix GTP v1.0: 3800 Performance
If at all costs I would stay away from the ZZP PCM. Caused my car to take a s**t from the piss poor tune they gave me. I would also recommend Will @ Overkill. His PCM's are pretty much bulletproof too. But the only downside is that you have to send him YOUR PCM to tune. And since he is on Canada, it might be a bit lol
