Is the 14mm head good for power upgrade?

 

Wow.

Yes, it is.

 

It should be one of the later steps though. Not one of the first things you do.

 

Unless you know where you want to be can't be reached with a 12MM H&R. The thing I've read about the 14 is the pump should be modded at the inlet and the front seal(c clip) to allow a higher PSI through to allow the fuel to cool it's internals. The front seal will usually blow out at around 20psi, letting fuel into the timing cover inturn into the crank case without a retainer.