What is the best option, I have a 2004 Grand Prix 3.8 V6 non supercharged w/185,00 miles. Would be best option be to swap to the 3.8 V6 w/supercharger or swap to the 5.3 V8?
No matter how much you may love your present car, the best option would be to sell it and buy the car you want. Changing the drive train on modern cars is a huge and expensive undertaking. Everything must be changed along with the engine including the transmission, the electronics, even the fuel pump. When you're done all you have is a homemade GTP which may or may not work properly. You will have spent a lot of time and money but will hot have increased the value of your car significantly. If you want a project, and have money to spend, buy a nice clean GTP or GP V8 and then do some performance upgrades. Then you'll have something. There are some great performance and appearance parts out there for these cars.
The supercharged 3.8 is a direct bolt in. Use the electronics that came with the supercharged engine. The tranny in the car will work although it won't be geared to make 'optimal' use of the new engine.
Search Pontiac Grand Prix Questions
Pontiac Grand Prix Experts