Trading in my 05 i got a great deal on a 07 Sierra Denali. What is the best mod for the 6.2 im trying to keep it mostly stock 403HP is alot better then the old 5.3. Trying to get the best milage who does the best mail order tune for these trucks cant dyno its awd. P.S. all my current mods will be for sale next weekend cam, springs, push rods all less then 1000 miles on them i wasnt satisfied so i moved up to the big dog.

 

I have the 08 Siearra Denali with AWD, which is identical to your new truck. I would say the best bolt-on mod for the money that I've done is the VaraRam CAI (noticeable performance over the Volant) and about 2 tenths of a mile better MPG.
Also, you can port the stock throttle body for a free HP gain (if you feel like bathing in metal shavings!).
Wheatley did my tune by mail order and it works for me.
I love the ARH headers on my truck, but they made it quite a bit louder and required a retune.
Best bang for the buck is the nitrous. I run a Zex 125 hp shot on mine that's good for about 1 sec drop in ET in the 1/8 (before the headers, VaraRam and Yank 3200 stall).
Congrats on getting the nicest truck out there, man. You're gonna love it.
BTW: here's a freebie: If you hold in the Traction Control button for ten secs, it will display "Stabilitrak disabled". This seems to put it in some sort of performance mode because I swear my truck runs noticeably better that way...

 

Thanks i cant wait to pick it up tuesday. What mpg's are you getting im a little worried feeding that big 6.2. Im a caddy tech i see what escalades are getting and it's not good. But as far as my plan im thinking i will do ARH headers, intake,stock catback and a tune. hope that will wake it up and help mpg.

 

Im in the market for a new truck myself and was wondering, are all the 6.2 denali trucks AWD??

 

nope. some are 2wd.

 

Need pics!!! Denali's =

 

Sweet! 400hp 2wd exd cab... Ill have to look into that!

 

That would be sweet but all denali's are crew cab. I think its about the only way to get a 2wd 6.2 though.

 

Damn it, i knew there was a catch! Well it still wouldnt be so bad..

 

I currently get 13.2 MPG (v.s 13.0 stock), even with the 3200 stall, which I installed right after installing the headers, so I really can't say how much the ARH's helped. But, that's definitely a "city" rating, since we have tons of stoplights, typical speed zones of 25 - 40mph w/ a maximum speed of 50MPH and more registered vehicles than people down here (seriously!). AND, since we have plently of stoplights, I tend to exercise my right foot judiciously! I only wish it had 4.10s instead of the 3.42 gears.
The headers and the CAI will help mileage, as will a good tune and sensible driving (which will be the heardest part!) IMO...