Ideally, sell it or trade it to SMI for the Air Force One if you have air brakes. They will give you a trade in value for your Stay N Play. If you don't go that route, you have to adjust it way down, so basically it will only come on in heavy braking. You don't want the tow brakes coming up as you're using the exhaust brake descending a 10 mile long grade. You might talk to SMI and see what they say too, they've always been very helpful with me. By the way, I had an old Stay N Play that I had on a gas rig but upgraded to the Air Force One now that I have a DP. Seems to work great, I'm glad I made the switch.
Brian