The blacktop has lighter internals which happen to be also weaker, but it's a bit more quickly. No hurt if you're not undertaking any large mods, but any pressured induction and you will be needing to uprate the blacktops internals. That is what the resistor pack on some versions on https://gunnergrbsh.blogpixi.com/26997841/top-guidelines-of-4age-engine-for-sale