Quote Originally Posted by Trump View Post
No need on the 91 octane , you can run regular 87 Octane if you want to just drive the car, and not race it. If you look at the manual for the 2004 GTP you will find that is states that you can run regular fuel in it. I owned a 2004 Grand Prix GTP and ran regular fuel in it and it ran fine. If you want performance then yeah run the higher octane. The Series III engine is very nice, I had no issues with it and the gas mileage was very good if you just wanted to drive it like a normal Car. The aftermarket air filter is very good for the engine to breath better, it helped mine a lot. I sold my car as Wife wanted a newer one so mine went down the road.
if you want your engine knocking alllll the time giver, but dont recommend that.