damn, burnin oil, but it seems to me that if you do ALL those mods, you oughta get more than 18 ponies. kennedy built a 50 hp 240. that's about 33 hp increase. seems to me that if you're gonna spend all that dough on all those parts/labor, you might wanna consider researching a few more builders.
as for the initial question, yes port and polish is a HUGE benefit. it's like a performance cam in a 4stroke. changes the intake and exhaust behavior as well as the transfer timing and powerband length. talk to angus at kennedy_power, he knows what he's talking about and he dynos everything.
pinkblasty's right, if you just do a p&p, you're just cutting the end of your dick off. you HAVE to have the head redesigned w/ the proper squish dimensions because the the stock head is a joke. also, p&p running on the the stock pipe won't run all that much better than stock. you NEED a proper pipe on a 2stroke to get any real power out of it. in fact, you need to know what kinda pipe you're gonna run and it's characteristics before you even talk to a builder about a p&p job, cuz that's one of the first things that any decent builder will ask you.
