Engine change after Q reg

[Big Vern]

At the moment the emissions test for all cars is whatever emissions test applied at the time of registration. This also applies in the case of Q plate so if you build a car with a pre '74 engine then it's visible smoke, pre '95 in non cat etc. Older Q plate kits (built pre SVA) are also visible smoke though there is some talk this could change as there has been a lot of confusion come MOT time with older Q plate cars.
It will no doubt all change again when VCA takes over IVA from VOSA!

BV.