My engine has a pressurized engine cooling system with thermostatically controlled coolant circulation.

I had planned to use the inline neck from CBS (Car Builders Solutions) but the Honda cap being much smaller then the CBS inline neck is no good.

I'm keeping my cooling system prety much standard utilising a presurised expansion tank.

i need to either get a simimar type of cap to fit CBS inline neck or another supplyer of in line necks?