I'll jump in here, as the (less than) proud owner of a bubba'd 1100. The barrel was cut down to 20" and because of this it does not feed reliably. I haven't shot it since I picked it up (on the cheap

) but the previous owner disclosed to me that it doesn't cycle trap loads well but heavy buck/slugs it will (I suppose more powder?)...
So, I would recommend NOT cutting it yourself (although yes keep it over 18.5" for the barrel and 26" overall then your legal) but if you really want a tacticool 1100 take the barrel to a smith an have them do it. It is possible to enlarge the ports on the barrel (Inside the barrel band/lug/ whatever you call it, and then it will cycle. But you probably can't do that yourself (I know I couldn't) so its best to leave it to the pros.
Also to the guys who jump into threads like this and say "oh don't make it a pistol grip you can't hit anything!"
First off, your wrong or your incompetent. If you can't hit something (were not shootin' skeet with it here) at say 10, 15 20yards with a pistol grip, your doing something wrong. Is it less steady? yes, but its not particularly difficult to manage either.
Secondly, the OP said he is doing a project here. He stated that HE WANTS a pistol grip. He didn't ask what YOU WANTED, nor did he ask if it was a good idea. He said thats what he was planning on doing. His only questions here were about barrel length and cycling function, so get off your high horse, and don't go mouthing off about how he regret doing something HE WANTS to his own gun. Jeez, rant off