I did the K&N CAI with heat shield & then I did the Flowmaster 50 series HD muffler from the cat back. I did not need to re do my exhaust piping because I have a SR5
That's about all I can think of for budget tuned hell I only paid 250$ total for both those mods the CAI was found on craigslist & the muffler was doen at a buddies shop