To SORN or not to SORN

[skoff]

My daily drive (2001 Lexus GS300) failed its MOT on a couple of holes in the exhaust last week. It turns out that a replacement is quite expensive, and difficult to get hold of. Only to be expected on an old unpopular mid range car I suppose.

I've managed to bring the cost down to a reasonable £550, less than half the price for an OEM part, by having a stainless steel exhaust made. The only trouble is that I can't get it in until October 13th.

I have re-booked an MOT for the 14th, but as the tax has now run out, should I declare the car as SORN until then, or just leave it?

I have another car to use in the meantime, which makes things much easier and the Lexus is off the public road on my drive, but I just wondered if I should by rights be SORNing the car for the sake of 2 weeks?