if i changed to a head with bigger valves and a mild cam would i need to change anything as regards to ecu's? to keep the fueling right?

 

MFI would need a setup again, and EFI would need a live map unless your running a generic chip of course.

 

AirMassMeter based injection systems, like the MFI is also, are not so vulnerable to setup changes. However, systems that are MAP-sensor based (Cossie, Megasquirt,...) need adjusting after every small modification.

 

Thats a good point, if it flowed more the flap would be sucked down further and so fuel more!