Port and combustion chamber design have improved massively over recent years, that along with engineering tolerances means that there is little to be gained by porting a modern cylinder head. Gone are the days like in the 70's and 80's when people like Yoshimura could extract massive extra power by removing masses of aluminium from heavy cylinder heads. There just isn't the metal in there anymore, the best you could expect would be to remove slight steps in the joins between the inlet and exhaust manifolds and the head but to be honest on a cost/benefit ratio it don't seem worth it to me. Just my opinion you understand, I don't know what you want from the bike but I don't think you'll get a big increase in performance by porting and polishing.
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