Something is really screwed up.

The system shuts down the fuel on the over run, unless you have changed the fuel regulator. So there should be nothing in the system to burn on the over run.

Turbo rally cars inject neat fuel into the hot turbo to keep it spinning under closed throttle conditions, otherwise the impeller would stall, hence the popping and banging of 'anti lag'

Other than screwing with the atmosphere with lots of nasty unburnt hydrocarbons and failing your next MOT, you'll be paying extra at the pumps for all the fuel you are wasting.

What you can't see with overfuelling is the 'bore wash'. Wet fuel in the cylinders will remove the oil coating and increase wear in the engine leading to a loss of compression and hence power very quickly.

Cheers

D

The old BL mini (pre cat laws) would pop & bang on overrun. The carbs dont totally shut off on overrun so fuel dribbles through. When there's enough mixture in the exhaust it can explode. With an air leak it pops a lot more.

Puntos having cats run a richer mixture (to feed the cat) and they have a spark on the exhaust strokes so an air leak will cause some really serious bangs.

The car needs a remap to run properly without the cat and it will probably still fail the MOT emissions test. A better bet would be a sports cat and remap. The sports pipe will not do much for performance without a remap.

V-Power is 97 or 98 octane. Engines with a knock sensor run more efficiently as the spark can be advanced further than on vanilla 95 unleaded. My HGT (with knock sensor) is actually cheaper to run on 98 or 99 than it is on 95. V-power also has cleaning additives so it could potentially dislodge sludge from the tank which should be caught by the filter. But if anything gets through it could block injectors.

That said, my 2001 HGT was run on 95 unleaded by the previous owner and I have used almost exclusively posh petrol (98 or 99 with other additives). I've never had any running issues.