Exhaust Help

[Driftaway]

Been checking out this exhaust on ebay for my car, and as I look more into it I don't think it's legal. Some help with this would be appreciated.
http://www.ebay.co.uk/itm/MAZDA-RX8-COMPLETE-3-CAT...

[Mastodon2]

Well, the bit that says "Decat downpipe" might suggest it's not. I can't remember if it is the law that all cars that left the showroom with cats need the fitted, but that is becoming standard for MOTing - previously, some decatted cars could still just about pass an emissions test, but passing is no longer the sole requirement, if your car had a cat when it was made it has to have one in place for the test. However, a friendly MOT tester may be willing to overlook this, and I've never heard of a traffic officer getting underneath a car at the roadside to look for a cat, if they could even get under the car enough to look anyway, or have any reason to want to look in the first place.

Rather than out and out legality, I'd be looking more at "Is the system quality?", "Is this going to make MOT time a total pain in the arse?" and "Can I get an already unreliable car with a relatively short shelf-life engine safely and reliably remapped in a fashion that will not shorten the life of the engine?".

Personally, I think the best option is probably to get a custom cat-back, leaving the cat in place. A good exhaust fabricator will be able to get you the look, volume and to some degree, the tone you are after.