I replaced the air filter on the 06' LBZ today and went ahead and removed the filter assembly when doing the change so to check out the intake tubing for any dusting. (Normal proceedure for me since finding much silica when using a K&N years ago----that product never never again). What I found on the LBZ is that the inlets that lead to the filter box from under the fender well are square inch wise, well less than the inlet into the box itself. I folded down the bottom flange of the upper inlet, the one that is ducted to the rear of the fender well. Then I used a pair of snips and cut diagonally at each corner of the lower inlet (about 5/8" each) and folded each side in and back to the inside face. This increases the total inlet volumn by 7 to 8 square inches; I didn't measure but would guess its close to or over the capacity of the air box inlet. Observation is that GM did a good job of isolating the hot air from the engine compartment----just didn't provide enough inlet volumn.