I wanted to post this before on my last message,but forgot.Superchargers are definitely the way to go when it comes to making even more power(like the 455 doesn't have enough to begin with!).I know they make a heck of a difference compared to a normally aspirated engine. I've got a 1992 Park Avenue Ultra equipped with the supercharged engine(first year for this engine) and it's a blast to drive. The torque is immediate and any rice burner that wants to test it is in for a rude awakening.I can only imagine what it would be like to have a supercharged 455 powered car.
As an owner of a 96 Riviera with the SC3800 Series II (240hp), I'll definitely second that! BTW, welcome to the board! Scott