a lot of times you pick up some false knock reading with the under drive pulleys and end up losing power. You'll usually get good results but sometime you don't. Reducing the rotating mass is a step in the right direction. If you have an auto, get a smaller diameter/lighter weight convertor. You don't have many options for lighter flywheels or clutches. You can take a flywheel to a machine shop and have them lighten it but then it's weaker and you must have it rebalanced. The LS1 F-body guys have an aluminum flywheel you can purchase but DAMN they're pricey. Then again, a good quality convertor is going to cost you about $800.