Greetings to All:

I am a new owner of an '07 Chevy Classic 2500HD with LBZ, having graduated from an '01 Chevy 2500HD with LB7.

Comparing the LBZ to the LB7, I am noticing a lot more turbo whine with the LBZ, which I attribute to the improved air box on the LBZ.

But I'm also noticing, sporadically, on a "cold" start, an intermittent "roar" under the hood with the LBZ - like the air intake is choked off and the engine is trying to suck a large amount of air thru a small opening.

I've checked thoroughly for any foreign objects, etc. and only noticed the baffle at the passenger fenderwell, near the bumper, was loose in the fenderwell, and that's since been secured by the dealer in its proper location via caulking.

But sometimes I still get this "roar" when taking off, after the truck has set overnite or at the parking lot during the day. Normally, all I ever hear is the turbo whine. Otherwise, the LBZ is so much quieter than the LB7.

Anybody have any idea what this periodic "roar" may be attributed to? Anything to worry about?

BradL07