A very funny discussion.
If a beginner does ask for an engine in the onroad section almost every advise is sending him to Murnan without any discussion if such an engine is to powerfull. What I am reading here is a complete different world and more funny to say, I had this same discussion on a Dutch offroad forum.
Yes, running a toplevel engine (mostly for a top price) should be fast enough. The cheaper models have some space to give that little bit more performance that the toplevel engines have and believe me, some small things you can do by yourself to get more noticeable performance out of any engine.