You're installing a cam with about 20% more lift. That means more wear on the valve stems an the stock guides. Headwork isn't all about porting an decking. Blue printing the heads and a good valve job along with bronze manganese guides give ya power and reliability.........

 

Bingo.

 

When I rode to WI for Fuel moto 2 years ago to do this build: 107, 555s, 2/1/2 pipe, etc. Jamie suggested leaving heads alone with this build...thought if I did 777s it would be worth it. I don't know much about this stuff, but it seems from the thread that his advise to me was about having the right combination already. Porting would have gained some hp and tq, but I have been really happy with what I have.