I've had first hand experience with this when I got a Rody Mod RB C5 on-road that I stuck in my Losi 1.0. At the time I already knew that on-road engines lack bottom-end so I installed a JP1, Losi clutch with all alu shoes and silver springs (heaviest springs) to get more bottom-end, but still wasn't enough. My local track is a medium size track so I could never stretch the top rpm of the engine. But overall the things was ballistic from mid to top.