Well I learned a lot about what to and what not to do to these vortec engines with my old 03 silverado on 36's to my new 05 sierra z71 on 34s.
Don't - Buy a CAI or throttle body spacer; why?
CAI helped, yes, but not to the point that I wanna pay $200 for one again. So I took the cheap way out and made the bottom portion of my stock air box look like swiss cheese and it dropped my intake temps by 10 degrees, next step is buy an intake pipe just to help flow a little and this is something I could fab up myself seeing as I have a pipe bender and the 4" pipe is easy to come by. Add spray paint and there you go.
I heard it all about throttle body spacers and the only thing mine did was take $100 and ate it. No noise power, no temp drop nothing. complete and total waste.
Don't - Buy mid grade fuel every time.
It didnt improve my fuel mileage for anything noticeable though I still run 93+ octane booster to clean her up every other oil change and my does it go quick but it does give you more power...
Don't - buy sylvania platinum or silverstar whatever they are headlights,
they are brighter yes but my Lord the bugs they attract and HID's are cheaper and brighter.
Don't - Buy headers,
the stock headers should be more than sufficient for any application you use the truck for unless your all out racing but then again, it's a truck?
Gears are the best power improvers you can buy, the leap from 3.73 to 4.10 is absolutley amazing.
Programmers may not be worth it for the 20 hp you get on the top end that most people will never feel but if you get one with the gauges (I hav a bully Dog) they are worth it in the accuracy of monitoring and the driving coach once it is set up makes a great improvement in mpgs because it will change your driving habbits if you pay attention to it's readings.
i LEARNED THAT A 2" body lift = a 4" suspension lift and a 3" body = a 6" suspension lift in tire clearance for 1/3 the price.
But mainly I find that the air box modification is the best thing ive ever done.
Just thought I'd share what i've learned with my trucks and share it with some of you. I'm only 19 and the amount of ignorance I had at 16 is amazing to me now. I thought that the more expensive it was the better and more hp i'd get. how wrong i was.......