my friend has a promaster. while it does have clamshells(which i think are way easier toget inside of instead of a tray), a nicer trigger, and better electronics(u cant adjust dwell in b2k4), you cant take the ram out quick, hoses do blow, and the reason the hose blew in this one is because we couldnt take the ram out to see a bad o ring inside cylinder assembly. we ended up sending it to icd. but stock, the promaster breaks a b2k4 in half and eats it. at the chrono we got 19 on semi uncapped without changing dwell and completely stock except for aftermarket barrel. it is way lighter and i like the way it looks.