Try going here: Performance & Billet Parts
remember that there are 3 pages of parts, so click on page 2 and page 3
and here: MANIC Mechanic Parts.htm
and here: Sick Bike Parts LLC - Performance parts for your motorized bicycle
and also see the billet cylinder head from Creative Engineering.
There is a ton of info on this site just by using the search facility and asking other members for their input.