Ditto on the rear sprocket - especially if you use it around town. I wouldn't go for a renthal alloy one again though as I hooked mine in less than a 1000 miles (although I was told that they do tend to wear a lot faster if you don't keep on top of your lubing routine).
Again, not a michelin fan - don't like the profile. Changed for Pirelli Diablos(?) which seemed to work well for me.
If you are going to be doing any sort of track work, rearsets are a must. After my first session at Mallory, I was grinding the pegs - the first time it happened, it really caught me by surprise so I instinctively tried to stand the bike up again. Fortunately, I had some rearsets I had never fitted in the back of the van (which I was hoping to sell) so at lunchtime, with a lot of help from Zimbo, on they went. Much better and no pegs touching down although because it did away with the passenger pegs, the pipes managed to melt the back of my Alpinestars. So remember to buy some pipe guards aswell or a few rolls of Duck tape (which I used as a temporary heat shield on my boots).
The shock is a matter of opinion - I used some settings that were given to me by Gary T (courtesy of MCN) just before Mallory. Raised the rear and then twiddled with a few other bits and it definitely steered quicker and it felt pretty good on the track aswell but .... I the let Dave Wood have a go on it and he came back on it after a single lap and said it was 'absolutely awful'. He then twiddled with it and it did feel better but not night and day so I guess that not everyone can feel the differences as well as some others. Having said that, the S4 has never let me down in the handling department. My suggestion would be to take it to Dave Wood who did a set-up day for the UKMOC and I don't think he charges the earth either (well, I hope not as he has my bike in pieces at the moment).
Oh, one last thing - a back protector - for when you start on those power wheelies.
Take care and see you soon
simon