Head specs are chosen dependant on what you tell me and what you ask for. (i.e. usually maximum forseeable power required is the main factor, as people tend to buy a head which a future bigger spec in mind. If you know exactly what you want, then chosing the right spec is much more simple!

Just to clarify, the waiting time is dependant upon what spec head you have. For my lower spec heads that don't require extensive porting I can normally do these jobs within a couple of weeks as I can fit the work in between other jobs. However when people order my big spec heads that require big ports, it takes me over 40 hours to produce such a head and as such it is'nt viable to do this jobs in between other jobs. As such I have a strict waiting list for top spec heads, and it does vary from 2 - 6 months at present!

In the future I hope to be able to speed up the production of heads and engines with our expansion and being 3 people instead of just myself, but time will tell!!