I just done my ST24. Left the standard calipers on there but got 40 groove discs and EBC Greens from CRN Products.

Great delivery, excellent prices, and now they've bedded in they're awesome.

Give them a call for prices 01246 559933

Discs were only £60 and the greens were £46.
Best option if you;re not looking to spend too much, and the fitting is simples.!

BRIAN