Disagree all you want, I'm speaking from personal experience with literally dozens of nitro engines over the years. Some engines are troublemakers, why only right now, I have a friend who's stock engine in his Bullet MT is a little ballbreaker, where normally those engines virtually tune themselves. I'm sure if I changed the carb it would behave better, but hey, I think it's good experience for the guy to have a finnicky engine for his first, things can only get better for him from there. I've also had a few HPI 4.6s that all behaved TOTALLY differently, some ran hot, some cool, some were a pain to tune, some weren't. I've also had very consistent RB v12 based engines I used to race. The difference you pay at the top compared to at the bottom relates directly to the quality of product you get, but I can also say that each one of those RBs, none of which were difficult to break in or tune, had different personalities on the track. This is something you start to realise when you can turn in 10 laps all within a half second of each other, then all of a sudden all the tiny changes that occur on your car are immediately noticeable, including the personalities of engines which effectively perform the same, just are somehow different. Who said anything about electric? Of course you have problematic electrics sometimes, once again you get what you pay for.