you will lose a little lower end tq, I have an ls2 intake and don't miss the bottom end since I have a 3500 stall. As for fuel rails, you'll have to modify your stock one tremendously to work or just buy billets from Edelbrock, about $80. Now if you have the truck injectors they might be too short to work the LS6 intake, never heard of truck injectors on a LS1/LS6 intake.