I think it has to do with heat how long the car stays in second gear. I believe with the higher internal gear ratio compared to the MTX-3 the MTx4/r is more prone to strip 2nd gear. Also if the 2sp engagement point is set too early I believe car stays in second gear too long causing the gear to heat up and strip. I believe I read that Mugen said this was the chief reason of gear stripping and that the gear softens with heat. The best advice I can for guys who strip gears is always keep an eye on your car's rollout as your tires wear you must compensate with gear ratio's. Also make sure your engine is not flat lining (engine reaches top rpm but no further speed increased is noticed) I know some people may not agree with my point but once I followed these precautions I have not stripped any gear since. You still have to follow all of the other points that have been mentioned in earlier posts.