I'm thinking of buying a performance chip for my truck for the extra H.P. and the extra mpg but mostly for the power. What I'm wondering is are these chips bad for the engine/computer in the truck. Also if anyone has put these in their truck already what kinds of gains did you get and what chip do you guys recommend. I have a 04 Sliverado 4x4 with a 5.3 stock everything as I just bought the truck ;P. Thanks in advance for your input.