I have read on here somewhere that the Brembo SP calipers differ slightly from the proper M4 Brembo, mainly on the piston sizes. However are they the same fitment 108mm is obvious but would spacers be needed to fit the into the Showa forks?
Unsure about the SP brembo's but the M4 brembo require you to take off the spacer from the fork bottoms on standard forks
I read an article about Brembo yonks ago, think it was Fast Bikes who visited the factory. They mentioned that an M4 caliper for an Italian manufacturer would be different to a Japanese one. They said the Italian manufacturer requires a stronger intial bite and the Japanese ones were required to be softer. They also soke about their MotoGp department and it was mind blowing ho wmany specs of the same caliper there were based on rider preference.