Haven't heard anything like that OBR1EN...
I would recommend investigating the liquid injection systems. I know people putting liquid injection dual fuel systems into VEs without any loss in power when running on gas!
Looks completely STOCK when the engine cover is on too (yes I know these pics aren't of a VE)...
Pic of the tank is in a Falcon, but it's the same dohnut tank used on the VE setup.