I have an '08 Mustang GT on order for lease. Can anyone tell me which is the best programmer to get, that wouldnt void my lease agreement, and how much HP can it increase it to? I see that there are cold air and programmer combos, but can I just use the programmer to increase HP?

 

yes u can get just a programmer and use it u do not need a cai but it definately helps as far as hp increases for the different programmers they tend to say around 15-30hp depending on which tune you go with as far as actual hp they give i dont know cus i did not have mine dynoed before and after the install but u can definately tell that there was added power dont know if this helps at all

 

first off, welcome to the forum...
now, pretty much any tuner or CAI/tuner combo is grounds to void a warranty unless you've got a pal at the local dealer. Now that being said, swapping the stock air box back and reloading the stock tune isn't too much work...
...I've read of combos yielding as much as 30rwhp...not bad for $700or so, and something you can do yourself to boot! I wouldn't bother doing one without the other...if you've got a MT use brenspeed, if you're a slushbox guy hit b*a*m*a chips...
...p.s. I hope you have an option to buy because I seriously doubt this will be your last mod! Just keep all your old parts so you can swap back when it's turn-in time...