Like Mot says, brakes are a bolt-on job... I bought his S3 calipers and disks and have fitted them to my bike, (91 Trident 900, green with silver engine like yours). Not road tested as yet, the brake still feels a bit spongy, I can pull the lever right back to the handlebar.
One difference was that the bolts that held my calipers on were too long for the S3 calipers, so I simply fitted the original spacers on the opposite side of the mounting lug. Seems OK and doesn't look too bad, I reckon.
The other thing was that I had to buy a longer stainless hose to fit from the master cylinder to the splitter - £23 from Sprint Manufacturing.
