Hi Leadfoot, the Kyosho MP7.5 Inferno MK3 has the older Kyosho GX.21 which is actually a very nice motor, no not the most powerfull high screaming plant on earth but with a bit of modding it can quickly be turned into a little monster. Yes it does hold a tune so long as you look after the rubber seals inside the carb. Its the GXR.28 that seems to have all the major problems but seems how I havent had one in my hands I cannot really say nothing about that engine. Probably just new people how have no experience with nitro engines not knowing what they are doing and cannt get them to run good.
Also the older GX.21 is bolted straight to the chassis where as the newer version has engine mounts, so do the all new .25 and .28 engines, which is a good thing. The .21 is the one to get though if you want to do the odd race here and there. It is fast enough straight out the box to win clubman races.[8D]