The cars been smoking quite abit and breathing heavy lately so first point of call was to clean the breathers, this made no differance. I also noticed a small mayo build up in the inside of the oil cap so I've done a compression test and this is what I found

Starting from cambelt side:
1 - 100psi
2 - 120psi
3 - 150psi
4 - 140psi

The car has a low comp bottom end with standard pistons and a cometic gasket, is it possible the gasket has failed? The car was rebuilt around 5k ago with a refeshed bottom end and new head etc so I'm abit confused as to how its failed so soon (if it has failed at all)

Any ideas chaps?