Heard that you can whack a 200 tire on standard FXDB (mine is FXDBSE but same thing i"m sure) which is 185 from the factory.

Anyone confirm this??? There is no tire rub inside teh guards etc / no bolts need to be shaved or anything??

No. You will need a 5.5" or 6" rim and tidy up wiring under the guard.
yes modify guard bolts is a good idea, may need new axle spacers depending on which wheel you get so a few small mods are needed.

oh yeah...

also pulley might need spacing over for belt clearance to tyre.

here is what I did:

http://www.hdforums.com.au/Default.aspx?tabid=71&forumid=24&postid=147309&view=topic

 i am in the  process of doing my 2013 fxdb. i will let you know how it goes.