Very cool Macca! I just installed my M4 SS last night on the stock head pipe.
I snapped the bolt that held the stock exhaust clamp. Cheap bolt + high heat = low torque sheer. Easy enough to replace with a higher quality bolt if I ever put the stock exhaust back on. I also had to cut/tear the muffler tape in the joint between the stock exhaust and head pipe. Found that it wasn't needed with the M4 SS.
What a difference in sound. No more sneaking up on people or cars, even at idle. Even with my Shoei RF-1100 on it is loud. I love the deep almost-hollow woop, woop, woop at idle, the growl under acceleration and the engine breaking sound that I just can't describe right now.
I just bolted it on and started riding. No ECU reset or anything. Seems to pull a bit more freely from 7K to redline. Haven't tried to hit top speed yet. It was a little too cold this morning at 36 F. / 2.2 C. The idle revved up to 3K this morning right after I started her up. A quick twist of the throttle calmed it down to 2K and then it settled down at 1.5K where it should be. I guess I may need to do the ECU reset, but I'll let it go for a little while longer to see if and how much it adjusts itself.
I want to take off the passenger brackets like you did, but I think I'll order some fillers before I take them off. Wish there was something on the market that would fill the holes and also give some protection to the rear brake reservoir.