Its coming up to my 1st MOT in a few months time so am trying to plan ahead.

Due to having a v long silencer and a 4-2-1 system I dont have space for a cat so am planning on buying a cat and cheap silencer that can sit in the garage and only come out once a year at testing time.

My query relates to the length and diameter of the silencer - my current system (03 R1) has a silencer 5" in diameter and 30" in length

is there any issue in relation to emissions with getting a short silencer (approx 14 inch) and possibly smaller diameter (4inch) ? Once fitted I will get the engine remapped for the MOT

thanks in advance

[Edited on 20/5/13 by markyb]

Are you on a Q plate?
If so then find an MOT station that only tests against visible smoke.

Got a new reg so a full test will be done and the centres in northern Ireland are still state run so no chance of finding a friendly tester