I know a guy in Montreal who has had excellent success with his heads among roadracers. His name is Tom and he runs TK Motion.

Before coming onto the Honda market, he was a successful NHRA record holder. He knows his shit.
He has worked under the guidance of a world class porter...who's name escapes me right now....I'll edit when I remember the guys name.

I have linked Tom to our site and this thread in particular...he should answer soon.

here is his site www.tkrace.com

Apparently he spends more time on the dyno and in the shop...his site is quite dated, as it doesn't reflect all the B18 and b16 (same head design) work he has done.
I do know one of his last projects was a turbo b18 GSR doing 500whp. Again, he has the details about that project.