I didn't say that it wasn't fine to use 87, I just said that I have only used 93. If I put on the mileage that some of you guys do, I might try a lower grade also. Just for the record, I use 89 in the Wing and my truck.
I have the Yosh slip-ons (not carbon) and both sides rubbed the swingarm in front of the clamp. I put washers in back of the peg hangers and it was enough that it didn't rub any more.