Its not like the domestics where you can buy cylinder heads. I don't know if there are any companies that actually sell cylinder heads for hondas. The most common head right now would prolly be the two mentioned above. A lot of guys are building VTEC motors that wern't origionally intented for VTEC (called LsVtec or CrVtec) and are doing some pretty serious headwork along the way. I'm assuming you do head porting? Bigger isn't neccessarly better on honda's, they are already quite well designed for higher rpms and any headwork should focus on the midrange a little more than the high end. If you over port your head, you'll lose the ramming effect (not sure of the technical name) and will loose power...and worse, your fuel economy will suffer.