What's the best way to lower my 07 kw9?

Car haulers use a different front axle. You dont need that axle to lower the truck

 

I have a airbag kit for the front of my Shaker, I'm currently on 8 bag air with leafs and blocks on the front. My Shaker dealer got me the kit which includes new offset shock brackets. I haven't had a chance to install it but basically the shock brackets and blocks come out, new shock brackets and bags go in, the ride is totally adjustable. It cost me $1G, hoping I'll have time to install it in the next couple of weeks. (Firestone bags)

 

I realize that they're differnent, that's why I mentioned it. They lower the truck about 4" without changing how close the axle beam is to the frame and the suspension has the same travel. If you lower it without a drop axle, the axle beam is closer to the frame, which may or may not cause problems. To lower 4" with the same axle, you lose 4" of travel and it can beat up the bumper stops pretty quick. Running mostly smooth roads, it may not be an issue. Here in the notheast, it can be a real issue.

If you can find a used car hauler axle, it may be the cheaper easier route to drop it.

 

Airbag adjustment ?

 

http://www.jonesperformance.com/categories/trukrodz/kenworth-trukrodz.html
Several different ways to close the gap without giving up suspension travel. My personal favorite is the "JP-K26K" extended fender sides (smaller gap) with "A" model headlights. I'm just sayin'...