Has anyone any ideas on cheap ways of reducing exhaust emissions for the MOT?

I have changed the plugs & air filter, is there anything else i can do.

Are there any petrol additives that do this?

Dill.

sometimes, if you bung a bottle of red ex or similar in the tank then give the old girl a good blast that would clear her lungs out a bit

Andy_sx

I always put a full bottle of Forte' Gas system treatment about 2 weeks before my MOT, and make sure i give it a good blast before i drop it in. i find staying in 2n'd gear all the way to the garage (only a couple of miles) does the trick nicely too.