stopping forced air being wasted sounds like a good call. will make some ally sheets at work.

Rainbird - the headertank cap sounds interesting.. as after a run when i turn engine off and pop bonnet i can hear the smallest bit of air escape squeaking from my headercap, its just a standard tank and cap. does this mean my caps nackered? think i got a fezzy cap in the loft which are the same fitment if i recall so will try that for now.

will invest in an alloy rad when funds allow