I 've always favored the spigot exhaust systems because of the ability to use the smooth clamps making a smooth clean mount. No one makes a smooth flange that I know of and the finned stock clamps just don't tickle my pickle all that much. However, once in awhile, and getting to be more so lately, I'll run across a set of the later style pipes I want to use. I really don't want to clutter that area up that much with the fins.

So, What I've done for awhile now is to have flat aluminum flanges made and use button head allen bolts to make it an all smooth zone. Heres some pics of what I'm talking about, below I just slipped a set on a mock up bike with regular hex bolts to show you in these pics. You can polish them.. plate them... or... what I did on a couple bikes was annodize them and have slots milled in to match the angle of the head and cylinder fins when they were mounted.

But .. doing all that makes for a pretty expensive set of exhaust clamps.. lolol... I usually just polish the edge and outer surface and mount them with button heads and call it good.. I don't sell these on my site, but Copperheadz makes them now and you get sets from him for $60 (plain aluminum). In fact he has a few sets sitting there now.. he just did some others for me. Just thing if you had a set engraved..