i was driving my xxx-nt today and i hit a crazy jump and rolled and it started to run really crazy loud. I checked temp it was at 248 so i shut it off. Took it to the side and after some tuneing i could not get the loudness to go down. So then i inspected the car mostly around the exhaust/header. I then noticed that i was missing one of the header screws!!! So it was losing compression and probably isnt good for it. So now i guess ill have to goto the lhs tommarow and see what screws they got that will fit. Because none of mine in my toolbox will fit

That happens alot especially in ready to runs, solution get two 4 /40 screws and two 4/40 nylon locnuts they make big size 4/40 and small 4/40 lock nuts ,you will want to purchase the tiny locknuts . put the screws through the muffler ,if you cut new threads its ok because your going to put the little tiny locknuts on end of screw & tighten .
Problem solved. Ps you might have to cut screws with dremel so screw dosent stick out so much , I had to anyway. They never came loose again hope this helps.

I had that happen to my NTC3 RTR. After I put in 2 spd then regeared it and many more hop-ups. It vibrated both exhaust screws and the screws that hold on the pull start and a few others. YES I use lock tite.