I have a 2003 Marin Nail Trail (26"er) hard tail, which has 2 pot Magura Julie disc brakes.

The forks are Rockshox Pilot SL. The brake mounts on the forks are IS (international standard).

I wish to upgrade my brakes to 4 pot.

Are 4 pot IS mounted brakes still available new. If not, can modern post mount disc brakes be fitted with an adapter? Does the adapter look a bit crude?

If I were to buy older 4 pot disc brake (IS mount) which models could I be looking at?

Also, if I change the brakes, would I have to change the discs? Currently have 180mm Magura Julie rotor on the front and 160mm on the back.