[Booty]

The fuel cut off valve works on negative pressure. When you lift the throttle the butterflies close in the throttle body causing the tick over switch to close to tell the car not to fuel. The resulting pressure build up in the airbox causes the fuel cut off switch to activate, effectively cutting off the fuel. Now, disconnect it and it keeps on fueling even when you lift off. Result.....some spectacular pops and bangs from the unburnt fuel going down the , now, already larger exhaust system. Sounds really good. Uses more fuel but sounds good.