I think the 4 valve motor cycle cylinders heads are pretty good design myself.

180 or so HP out of a 1 liter, 1000CC's

200 or 300 HP Ninja for 2015 1000 CC's

https://www.youtube.com/watch?v=vAo0LWQFxdE&feature=em-subs_digest

MBHD


12 port SDS EFI