which ever fits your budget best.
Without a tune, the gains from any of the flavored intakes is nominal.
I have the Volant Gen 3 on my 08, and I felt a difference, how much better is it over stock?
Don't know. Sounds better though
I also have the Magnaflow Cat-Back, How much better is this over stock?
Don't know. But it sounds better
I have the 2* timing advance, how much better is that over stock?
A lot better
I have not done a dyno run, with AF readings, So my opinion means little on which intake and or exhaust is best for our trucks, everyone has their preference and what they believe works for them, so take it with a grain of salt.
Do a little more digging on the site, there are those that do avid track runs, and tried multiple combos of Intakes/exhausts and found what works best for them.
Goodluck!