If I remember right, the sensors are located in the chasis (in the crumple section up front), the airbags will deploy with a direct hit @ 8mph. I do know that the sensors are NOT located in the bumper, so hack away! Just know that a fabbed bumper will be more rigid and will be more likely to deploy when off-roading. I will be making a set of bumpers for myself shortly and plan to make an airbag disabling switch to turn the airbags off while off-roading. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Good luck with the bumpers! <img src="/forums/images/graemlins/cheers.gif" alt="" /> Post some pics when you're done!