I am using an Omex engine management that will cutout the fuel pump after the engine stops. Question is for SVA do I need any additional cutout in series to stop the fuel pump in event of accident, or is the one in the engine management sufficient?

My MBE has the same feature and was fine for SVA

So why all "regular" car have inertial sw?

Thanks guys

I think in case of accidend if you have an inertial swithc fuel immediatly stop, if not you have to hope engine will stop by himself to have fuel stop, and hope too in the while there is no fuel leak.

I'd still put an inertia switch in the rear end of the vehicle - that way if you get fecked in the rear (i.e. engine and ECU all OK therefore engine stays running), you'll still be safe...