Sig Cap231EX w/OS 1.08???
I had an MDS 1.48 in my Sig Cap and it performed fine. It is now in a DP Ultimate and works well there too.. As with ANY engine, make sure that there is as much "outlet" area as "inlet" area and you should be all set.
If you go with a BCM muffler, you will end up cutting a long slot in the bottom of the cowl to allow it to slip over the exhaust outlets. This should be MORE than enough to provide proper cooling.