Every engine has it's own quirks that can be exploited for more horsepower, better throttle response, etc. What are the ones for the 4.8/5.3 vortec? Ive heard talk of the TBC bypass, MAF relocation, and insulating the fuel lines, but do these really do anything? and are there any others out there?

 

The best value thing you can do to them would be to get it tuned, and maybe replace the intake tube (airbox/filter is fine). Don't waste your time with the stuff you mentioned.