My head is skimmed right into the valve seats , I've not recessed them or anything, it's running 460 bhp dyno'd with nitrous (400 nitro jet and can't remember the fuel jet) I kick its head in everywhere and done 3 track days one of which it was borrowed for the lancs rs show at Anglesey and was driven hard by 3 people giving passenger rides all day non stop never let me down once!