Can we drill holes in the stock box to help get more and colder air in the box? If so where and will it suck up water from the many rain storms we have in so.cal...lol. I have a stock 2005 LLY work truck with a muffler delete. Because its a company truck and don't want to put money in it when I get a new one every three years.
Derek

Here you go. Just go to duramax lly and tech tips. http://www.kennedydiesel.com/

Swiss cheese airbox? Did you do the same thing to your box? No codes or water getting in?

I did it on my 03. also take a look at Diesel Power's site whackywhack.com The pics are burried somewere on there and are fairly helpfull.

Or get a new LBZ or updated air box. They seem to be very nice peices.

I cut the side of it out. I did not start drilling out the bottom. No problems and no water in there. But there are a few more bugs in the filter.

After some research I have decided to add a homemade 4" ram air intake to the stock air box. Yesterday I ran a 4" aluminum flex dryer vent hose from the airbox down thru the front support structure between the horn and headlights. It then turns left in the space behind the bumper and ends where the air intake slots are in the bumper. The plastic shroud between the frame rails below the radiators is flexible enough to pull down to reach through the space for working the pipe into place. The horn wiring needed to be adjusted by opening the harness ties and lowering the harness to make the horn pigtail about 1" longer, then reconnecting the clips. After loosening the horn and rotating it so the wiring connecter tips to the left there is just enough room for the duct to squeeze through. The airbox is just big enough to cut a 4" round hole in the lower right front corner next to the fender below the filter. See pics from Kennedy's site where he cuts out the box. I haven't completed it yet (need to buy 4" holesaw tonight) but I am planning on mounting a metal ducting takeoff flange to the box to clamp the flex pipe to. If this works I plan to replace the dryer vent hose with T-7NW or T7-SR 4" flex hose from ducting.com. This is a flexible chemical resistant thermoplastic hose with smooth interior and -40 to 275 deg temp rating, more suitable for automotive applications than dryer vent. I am still working on how to build a rectangular-to-round snorkel that will grab a slice of air coming thru the bumper and force it into the hose. Since the hose turns up behind the headlights I think any water should work its way back down and drain out - I suppose it might be possible to slug the whole tube and fill the air box if driving through very deep water, but I have also left the original opening in the box open next to the fender, so it should drain out there. This is quite experimental so far, but I felt that just opening the air box would still allow all the heated air behind the radiators into the intake. Other than cutting the air box it hasn't required any irreversible changes to the truck. I also cut out the opening in the silver tape between the airbox and the fender and may try to weatherstrip the gap later.

Will the stock airbox from a LLY fit the LB7? I have one laying around if it would help performance. Anyone else getting water in the swiss cheese airbox? Only one answer so far.

the Chevy dealer said that they have an upgrade for the 05 airbox. They're putting and 06 box & tubing on them now. It draws fresh air in from the front bumper and not under the hood. $1000 upgrade for free.