Originally Posted by Whirlybirds
I guess I'm more concerned about increased IBU's.
You're only really going to get an increase in bittering IBUs from the amount of time (the longer it is the more IBUs gleaned) and weights of hops used during your boil. Hop additions during the last 15 minutes will contribute to flavour and, to a certain extent, aroma. Hop additions after flame out will mainly contribute to aroma. Leaving your hops in during fermentation is not going to net an increase in bitterness, if that's what you are worried about, and a lot of people leave hops in their fermenting brews until bottling time.