another strong point to the spiral heads is depending on your riding habits you can probable ditch the radiator fan and not have heat problems just my two cents.

How hard are the girdles to install? Are there any that can be installed by the do it your selfer?

 

better and higher cooling capacities and you can change dome depending
on what range octane gas you will run is the most benefit of the billet heads,it does add little torque tough...

 

also I retorque my cylinder bolts monthly is a girdle still needed if I'm being this fanatical?

 

If you get any portwork at all then I would do it. Mine grenaded on me with just a trail port.