if I put an overflow catch can on the radiator will that require a different cap inorder to let the coolant back in to the radiator ?
No your existing cap will work with a catch tank, pressurised radiator caps have to let air bleed back in through the overflow and past the rubber seal when the motor cools, otherwise the radiator hoses woud collapse as the coolant shrinks. If you fit a catch tank the radiator just sucks in coolant instead of air.
Stuart.
