porting and polishing intake and exhaust ports

[Stuttgart]

what gains am I looking at, I know a polisher that will do it at his shop for free in his spare time as a favour to me. What gains will this bring on the dyno? Both intake and exhaust ports will be mirror polished. 5bhp gain?

[propr'one]

i had some minor intake and exhaust polishing done, very minor gains, although it was not done fully. from what i've been told, its not really worth it