Hello my name is Greg and I have a 2005 Buick LaCrosse with the L26 3800. I know it's not a Grand Prix but it's the W-body sister car to the Grand Prix, and the only other model with the Series III 3800 engine option. I've always been a GM guy at heart owning several of them and have always loved the W-body platform. I also have a 2004 Silverado Z71 pickup that I drive time to time when needed for truck duties.
Anyway, I'm planning on top swapping my car in the near future and there seems to be little info out there on performing this feat, especially on the tuning side of the spectrum. I have most of the parts to perform the swap, but my main hurdle is going to be tuning. HPT doesn't support my car, but they do support the Grand Prix (go figure lol).
This looks like a great forum and I'm eager to learn a lot about the performance capabilities of the W-body platform.