One of the well known mods to the head button is the teardrop above the exhaust. RB had it standard in their C5-Rody modified but did give later a free exchange to a normal button head, do not know why...

I had a long discussion with Mr Singh and he advised me to start with 3 and indeed one of them above the exhaust. I did notice a stronger shifting to the 2nd gear with ny onroad so the claim of a wider powerband is true. The other claim of less fuel consumption I did not notice.
On the other hand my friend did try the same mod on his 23cc bigscale engine and he did notice a longer driving time on one tank. For him driving 30 minutes on one tank was critical but with th 3 grooves he did get some extra minutes and he also did notice a wider powerband. Because the combustion chamber of such bigscale engine is in one piece with the cilinder it very difficult to get the grooves in so he is making them into the top of the piston.