I have, I think he should seek contact with Hero Motocorp, they have the best version of that engine. That engine can be bored out, but currently does not qualify for street use. To get the most out of it and to meet emissions it needs EFI. Hero’s version has EFI and is rated at 20hp. But that is certainly not enough, he should also pursue Hero and Takegawa simultaneously for a 15hp horizontal DOHC 125cc engines, for production street bikes for the tier one in the EU. That would be about engineering prowess, it was Buell that took the 223cc to 20hp. I wonder if it also meet emissions? Only the Japanese offer full or complete specifications and only in their domestic market. They list models with power ratings as well as emissions, they also always offer accurate numbers, at some point in their evolution the government required it and also that it be 100% accurate. I do not believe a DOHC would be dirtier, it likely is more efficient. I believe that it is all very possible and Asian manufacturing is cost effective enough to bring it to the markets affordably.