The classic sti brakes are the same as the uk turbo etc. I have to say the standard 4pot brakes are pretty woefull on the classics, i ran uprated disks and pads and fried them on the isle of man in less than an hour and they never really gave much confidence.
I was lucky enough to have a set of AP 4 pots on my type r and they were night and day, depending on your budget an upgrade kit maybe a better option.
https://godspeedbrakes.co.uk/products/subaru-impreza-gc8-300mm-brembo-caliper-kit
thats for a gc8 classic, but something like that would do the trick, would need to confirm fitment though.