Im sure the Mot states:
Do all 93 on cars have to meet the cat standards?
Several post 93 cars have cats fitted but are only subject to the none cat test. This is usually because they have a carb fitted or the manufacturer has not submitted data.
I have a post 93 car, if I remove the cat would it still pass the MOT if the emissions are OK?
There is nothing in the MOT regs to say a cat has to be in place but if the vehicle year/spec says it has to be tested to cat emission standards then it would be done using cat specs. If the car met those limits without a cat then yes it would pass.
Will a 1991 built car, thats imported into the UK in 1999 be subject to cat standards testing?
From the testers manual.
Vehicles fitted with modified engines
If an engine has been modified in any way, it still has to meet the exhaust emission requirements according to the age of the vehicle.
Personal Imports
The vehicle will be tested according to its age from first use. The only exemption to this is if the vehicle owner can present to the tester at time of test a letter from the vehicle manufacturer stating that that particular engine as originally installed could not meet the equivalent British emission standards. If this is the case, then test to the next lower emission standard.
eg. A 1995 car first used in Africa has a letter from the engine manufacturer stating that the particular engine (engine number to be stated) cannot meet Catalyst emission limits, then use the pre cat limits of CO 3.5% HC 1200ppm.
Vehicles fitted with different engines
Test according to which is older, engine or vehicle. eg. 1995 car fitted with a 1991 engine (of what ever make) test to 1991 standards for emission purposes.
NOTE: The onus is on the vehicle presenter to prove engine age.
(taken from
http://www.motors.freeuk.com/faq/mote.htmhttp://www.motors.freeuk.com/faq/mote.htm)