yea i just got a NS4 and i let it sit to do its thing and it sounded like it was at full throttle(this is my second RC car) i just took it in to my hobby shop to let them fix it cuz i did not want to mess with the car (maybe when i have a little more confidence in myself) lol sry this might my a long post when i got my first RC car it was fine during break in so then i thought to race tune it and i blew out about 4 spur gears till my stupid mind finally thought to read the manual so it said to tighten the diff. and added some locktite to the engine mount screws and it made a world of difference