hi all im currently in process of refitting the head after what turned out to be the longest rebuild in history dunno.. lol anyway whilst its off im looking into some performance mods i can do ive ordered some new uprated pistons/cams , de restricted the box, removed precat and am going to buy a 2.5" sports exhaust system. now im wondering if a good old port and polish to the head would be a good idea whilst its off, has anyone done this and if so how much money are we talking and what gains can i expect? cheers..