My rzr 1000 has been backfiring on me for a while now. It all started with my two brothers racing exhaust. After a few rides with that is backfired like crazy..to the point where it stalled out.

I then installed a power commander programmer. That fixed it for a while. And its back again.

Heres the weird part. It only happens after riding for a long time. Eg) Ill ride for 4-6 hours without a backfire. Obviously im stopping and starting with the beer breaks and that. Then after riding all day itll backfire when im above 50ish km/h. So ill take it easy and slow down a bit. Then itll start happening at 40ish. Then lower and lower. By the time im home im pretty much limping.

Another thing. Everytime it backfires the headlights and interior lights go out. almost like all power is lost for a second. Except my light bar and stereo. They stay running.

Wtf could be causing this??