2004 5.3L 4x4

[RJQuick]

I have 127k on my engine and the truck runs great. I am getting ready to do a tune up and wanted to find out what type of performance upgrades and in what order actually make a difference in MPG and in HP/TQ. I'm currently 100% stock.

 

I am not looking to make this a ridiculous build, I don't need a loud abnoxious sounding truck. Looking for best bang for the buck mods.

 

Thanks,

Roy

[Carder09]

Headers w/ custom exhaust. And a tune will do you best.

[GMstrong]

^agreed,Plus a aftermarket drop in filter youll be happy.

[RJQuick]

Thanks for the guidance. I've seen a lot of exhaust and header systems out there. Any brand recommendations, I know that sometimes you pay for name and not necessarily quality. Also, I'm in California and our emissions regulations are strict. Will aftermarket headers pose a problem?

[uh6tdrvr]

Headers and tune will give you a noticeable difference but it will be louder with headers. A tune alone would be the most noticable since they are custom to what you ask for. If everything (current exhaust) is good and you just want a different sound I would go with a muffler of your preference. Youtube will give you about every combination possible. So with all of that being said, I would start with Plugs and wires and a drop in filter of your choice. There are NO proven HP gains from a reusable filter and minimal from any aftermarket intake(K&N or any others) just less filtration with one. Even though it may not seem to need them, 100K is the recommended interval. Also I would do a Trans filter change, it will take about 5.5 qts to top it off. Personal preference but I would change to Synthetic oil but thats just preference.