I'm looking to replace the OE back box on my Terzo with a performance unit along the lines of the Scoobysport exhaust. Another option which is told (as an old wives tale or urban myth) is that bypassing the catalyst will give increased performance.

Is there any *real world* performance advantage to be gained from removing the catalytic converter and replacing the exhaust with a complete straight-through system.

Will it screw up the readings from the lambda sensor? Is it legal? What about replacing it for an MOT test?

Feline lovers do not despair. The cat will probably stay on unless anyone recommends otherwise.

It is most definitely illegal, but that doesn't stop people doing it.

There are power gains to be had (I don't know how much exactly though), but is it really worth killing the environment and getting a hefty fine and points on your licence if you get caught.

I believe it is possible to fit higher flowing Sports Cat's, which do the same job as before, but with less restriction.

Killed the cat on a 98 model replaced the compleet exhaust starting at the turbo with a 3.5 inch full flow-pipe. The performance inproved a lot, less turbo-lag, better performance 0-100Kph under 5 sec. The only problem i had was that my turbo pressure became to high so yhat the dumpvalve opent in al gears( turned the pressure u little back so it is within standaard max-pressure +/- 1.15 Bar)

JP