Your warranty will still be valid. However, if the modification results in damage (burden of proof is on the dealer) then the dealer can refuse to fix under warranty. This is my understanding from other posts. Also see Magnuson Warranty Act.

 

i put some bilsteins on my 2010 suburban today. improves ride

stiffer ride with less perceived body roll. handles curves on the highway better and tires hug the road.

i like it.

 

17" wheels w/ stock tires will give you a softer ride than the factory 20s. Especially if you just inflate to the recommended pressure. It's almost mutually exclusive to have a soft ride and crisp handling, especially w/ a live rear axle. Hard bushings and bigger roll bars will definitely make the ride harsher.

 

Put Michelin tires on it...big difference for me.

 

Look at your tires before you get into anything that requires you to change anything that might void your warrantee. I agree with the michelins. I have michelin cross terain suv tires on 16's smooth as silk. On my 20s i have Falken Z1EX 275 55r20 they ride almost as good but better handling in corners. Look up on the review for the current tires you have on your truck. That could be your culprit there.