Some mod the bracket, some don't.
I just installed my K27 Hyflow-S, but didn't have time to mod the bracket this weekend before going to the track. When I get back I will. I think it's a good idea.
BTW. Sonny is selling a new HF or HF-S at a great price. http://forums.rennlist.com/rennforums/showthread.php?t=314347