Same here, I race my X-fire at Willow Springs & Button Willow Receways and always turn it off and have no problems... The car has a built-in REV limiter which cuts the engine slightly over red-line (6200). I have inquired to all CHIP TECHS if they can eliminate the limiter and they have all said no.

Perhaps your rev limiter is srcrewed-up or the tach is not right and showing you 3500 rpm when you're actually at 6000+