What size for the mikalor clamps?
They are W4 63-68mm. (W4 being the width). The bolts are stainless so are likely to strip if tightened too enthusiastically. The factory use Holts exhaust sealant on those joints which guarantees they
don't turn but makes disassembly more difficult.
. They just slid off after undoing clamps and supports, which did surprise me as was expecting a fight.