The Mr2 inner wheel arch was never designed to take a large wheel, when DNA designed the kit it was one of the problems they had to overcome, that's where the hammer comes into effect. Bear in mind the guys made this kit as user friendly as possible, no welding, standard tools etc....
To get the correct tracking width both wheels had to be pushed out, the DNA standard way was wheel spacers, here lies another problem, the swivel arc of the front wheel then becomes larger and fouls on the rear inner arch, here's where you bash it with a hammer. The standard 19" wheel then fits the car
Several methods allow for 20" wheels, bash the hell out of the wheel arch, some builds comment on the footwell splitting from the hammering even on the standard kit set up, the top lip seal also needs tapping up, another method is to move the swivel arc out using a wide track kit, this takes out the necessity for wheel spacers also reducing the left to right swivel arc, you can now fit 20" rims. This is a lot of work for an already finished build.
The choice is yours, I'm already set up for 20" wheels, but my suspension is Audi and not Mr2
I'm always interested in ways owners improve their cars, maybe this will be how you do yours
Darren