Possible catalytic converter failure...need advice

Hi folks, I'm from sunny South Africa, driving a 2004 ZR160, pre-facelift model for the last 9 years, and suspect my cat has either failed/clogged/poisoned. Apologies for the long read, but concise information is required.

These are the symptoms:

- Driven hard, the hydrogen sulphide (rotten eggs) smell is evident

- Slight hesitation between 5-5.5k rpm

- Taking off, with little throttle, the car hesitates between 2-3k rpm



I took it in for a diagnosis, all the sensors are working fine (throttle position, camshaft, crankshaft, map) including lambda sensors (which switch from lean to rich, although according to the auto electrician, is a little slow, but fine). Diagnosis picked up a misfire, but not pointing out which cylinder it could be. When idling, there is no misfire detected, but when you rev the engine, it picks it up. Returns to idle, misfire gone...very weird.



I changed the plugs, leads and coil packs three months ago, so that wouldn't be the problem. In SA, we don't have emissions laws, so removing the cat is not a problem.



Would the failed CAT cause the misfire and hesitation?

By removing the CAT, will this affect the overall running of the vehicle?

The car has a catback (removal of the middle box), with the original backbox, would this be sufficient backpressure for the motor, without undue strain on the components?

I would just remove the cat and fit in a pipe, with something we have in SA called a "mini cat", which fools the ecu, so the engine light doesn't come on, with the current system, would this be sufficient or would I need to change the backbox and refit a centre box to ensure sufficient backpressure and a not so noisy exhaust?



Thanks

Ash

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