Originally Posted by KTiM
Apparently there is a benefit to be gained from having a HiFlow head on an older engine. Sommer do what they call the "red head" flow job on older heads which, they claim, takes the head to better than a stock HiFlow. Also their advice on airbox mods varies for the HiFlow - Older bike = airbox door but leave the snorkle in, whereas HiFlow = airbox door and remove snorkle.
I would go for the Sommer solution.
It is a handmade High Flow with finishing touches.
Or send your head to Mr. Creep
I think I will send the head of my spare engine to the good ol' US of A