The Leo system looks very well made Zerodog! I found the Akro a little 'tight' in areas. The mounting of the muffler is also a little vulnerable like you have stated. The carbon mount loosens with every 'ruggered' mile and creates a bit of play. A second mount is a good idea.
Starter motor housing on my 05 has about 1mm of clearance from the Akro header and the outer fuel pump housing of the FCR (mines a 41 mx) is a little closer than desired. I had a fellow member try my old header (original) on his '98-620 LC4 with the FCR (non mx) and it fits with oodles of room. I think I might have got a P.O.E.T.S (piss off early, tomorrows saturday) pipe out of the Akro factory.
Big difference with a decent pipe and the FCR isn't it!
I'm about to put a 45 rear sprocket on mine as I could do with a tad more revs down low in the tight stuff.
Still haven't got around to fitting those springs and valve shims.
Gettin' mighty quick at changing diapers though
'05 640 Adventure