LFCinSA

hello folks. having read as many v6 to v8 swaps posts as i could find, it appears it would be easier/cheaper to just mod my stock '03 reg cab manual tranny v6 with 56xxx miles instead. classify me as a 'normal' driver not too heavy on the pedal, just would like a little extra 'oomph' when i need it. my bicycle is the most i put in the bed and unless an emergency pops up i don't tow anything either. these are the mods i THINK i need, but please correct me where i'm wrong!!!
1..CAI- would go with k&n
2..headers-necessary or not ?(if so what is a good brand for the 4.2L, if they even make headers for the 4.2L)
3..dual exhaust-prefer a deeper vs louder sound if possible, what's a good brand for this in the 4.2L's?
4..custom tune-i assume i would wait on this until AFTER all the above mods
are done? also, does a tune actually increase hp or just make better use of the hp the engine already has?
i'm just looking for the best 'bang for the buck' mods. thanks for the help!!!