legal requirements for exhaust mot

hi , curently building custome exhaust

i know it musnt leak gasses, i know it must be behind drivers door at least, and i know it musnt be too looud and since my cars after 92 it must require a cat


but is it legal to just have the one silencer and thts my backbox ?

aslong as it meets the emissions that is it has to produce below 0.3 carbon monoxide, below 200ppm hydrocarbons (unburnt fuel) and lamda of between 1.03 and 0.97. If your exhaust leaks anywere even a pin hole it will suck in air and rase the lamda and with out a cat u will be VERY hard pushed to meet the CO levels. If I were you I would look at finding either a 100 or 200 cell race cat as that should just scrap through.

No were does it state how many boxes you have to have, all it states on noise it that the vehicle should be of the same noise levels as another standard car of the same size.

im keeping everything on the cat atm, just rebuilding teh cat back so everything should be fine then


cat gets removed llater afetr mot lol