Check to see if your rear shocks are holding air, they will sometimes leak around the ballast and you'll be stuck buying new shocks. There are a few places online that sell them for a hell of a lot cheaper than the dealer, or you may need a fresh compressor. Mine continues to get louder and louder so I'll be retrofitting a viair with higher cfm to replace the stock unit, it also depends on where your autoride links are adjusted out back (to tell the truck how far to fill the bags). When I lowered my denali I replaced the rear links with shorter ones but had to pull them off later and grind them a little shorter so it wouldn't lift the rear of the truck.
