The supra sure is able to go through the MOT without cats (well at least the first cat and likley the second i reccon too).
At my MOT last year, the garage was unable to find the Supra N/A on their list of cars on the DVLA database, and hence they didnt have a specification for the exhaust gases.
Apparently in these cases (by the sound of it any import car that wasnt available in the UK), the DVLA dont have exhaust gas specs and they therefore use a very high max limit as a fall back spec for all of these cars.
The limit that was used for mine was 3.5% for CO (apparently most cars have a max limit of about 0.2%) and max HC was 1200ppm (not sure what a normal limit for this is)
To give you an idea of how my single de-cat N/A came in, in terms of results, my CO was 0.206% and my HC was 156ppm.
These are well within the limits the MOT uses for this car, and hence it could be running like sh*t and would still pass, you could mod it like hell and it would still pass.
Some of the traders on here must come across this regularly and will be able to advise far better than i can, but this was my experience last year. By complete chance my MOT is tommorrow so i will let you know how i get on this time around.