Ride height was the reason. I wanted it level unless towing. It sits about 1/4 inch lower in the front with the rear overloads removed. Added the airbags so we don't sag when towing. Mounted the subs on side in the jack area in custom fiberglass box.I figure if the intake is too loud while towing I will crank the tunes a bit. The van hits an impressive 148 DB which is very hard to do with a vehicle this size.