i've had the next for about 6 months now, and the engine is holding great. as far as the tuning issue goes, it's not that touchy, i just broke it in and tuned it to abou 220-230 degrees, on 30% nitro. definitly replace the diffs with the metal ones, for the price(around 20-25 dollars, after shipping), you stregthen this truck ALOT. i took a stainless screw and plugged the pressure line, sealed with high temp silicone, and drilled a hole and put a pressure nipple so i could use standard line. i did have some trouble with the on/off switch going bad, so i just bypassed and removed the switch, now i just use the plug. also, it is a good idea to take the back plste off and seal it with high temp silicone, the carb also. Isealed the muffler where it comes together too, just in case. I hope this helps anyone, because this truck runs like a little missle, i am definitly enjoying mine.