I have a stock LT1 with just a few bolt ons, Mac Midlengths, SLP Loud Mouth (well it will soon), etc and I am thinking about buying the GMPP LT4 Hotcam kit with Roller rockers. What kind of decrease in gas milage would I notice after install. Also what all is required in putting a Hot Cam on a LT1, do you have to pull the motor? Or Better yet, does some one have step by step instructions?