My neighbor has the 08 Sierra 4-door black, and just installed a 6" Fabtech lift, and its rollin on 35" Nitto's with 20" rims. The truck looks awesome! but it has no *****, and your constanlty having to stab the throttle on the highway to keep the RPM's up. He really wants to keep this setup, but needs more power. I suggested a programer,intake/MAF,and exhaust; will this be enough to actually get some "GO" out of this truck?

 

re-gear the truck for those 35s.

 

I 2ND that 100%

 

Is it a half ton or 3/4 ton? What engine? The reason its so slow is number one like its been said it doesnt have the gears to push those 35's and heavy 20's, you need 4.10's or 4.56's to push 35's. What gears does it have stock? If it has 3.23's or 3.42's it wont be able to get out of its own way. You can look up the RPO codes for the gears in the glove box: GU4: 3.08
GU5: 3.23, GU6: 3.42, GT4:3.73, GT5, 4.10 G80 factory limited slip. I would re-gear to the proper ratio then do Intake, ditch the maf, they dont do anything the factory one is fine, Custom pcm tune, long tube headers, exhaust, underdrive pulleys. Then see if you like the performance your at then. If not there are plenty of other things you can do

 

Re Gear before you break everything
Wheatley Tune
Intake
Full Exhaust
cough...magnacharger...cough

 

LOL, the reason why the truck feels slow is because it's a 4 door with 35" tires and 20" wheels. The Fabtech kit also added some additional weight. You answered the question in your original post. Just like everyone else said, get some deeper gears and make sure you get a tune afterwards.

 

I'm with all of them. Gears and a tune. CC's are heavy enough stock. add in the weight of the lift kit, the 20"s and the 35" rubber and you have a heavy beast.
Start getting some bolt-ons and it'll start pickup itself back up off the ground.

 

Sounds like my neighbor who tried to "copy" everything that i did to my truck. Whenever i did anything to my truck, within a few days to a week he'd have something very similar. I put my lift kit on, he put a lift... i got wheels and tires, he got wheels and tires... i put on an exhuast, he got an exhaust. he basically copied everything he could see. Long story short, he ended up getting with 37" tires, 6" suspension lift, 3" body lift, powered by a 4.8L w/3.23 gears on a 1500 and he's curious why a mom with stroller can beat him off the line. He still shoots his mouth off how he has a K&N drop in filter and exhaust, but doesn't know why he lost so much power and MPG

 

ohh... and he still asks me what my gauges do and if he should get some.

 

Oh brother....