impact wrench axle nut

I got a 5.7 cfm @90 psi air compressor in the shop, had a incredibly cheap impact wrench (Ingersoll Rand)(from wal-mart, cost less than 50 bucks) that isn't very strong, and is over 8 years old, almost useless. I need a new impact used mostly to tear apart suspensions/axle nuts and lug nuts...