If you you make the tourpak detachable you will gain an extra inch or 2 anyway.
One thing you might want to check is to make sure your tourpak is set to the back position as Piper said. Most dealers sold them that way but someone could have moved it up, when you look down at the tourpak with the liner removed the bolts should be in the hole closet to the seat - a side view will show you this. It makes a HUGE difference if the tourpak is set forward - there is almost no room.
If you are a little guy

I would buy the detachable hardward first - I made mine detachable and it does improve the space also when you take the tourpak off and put a sissy bar on the rider can sit back further. I know alot of guys have used the George Anderson kit my concern is with the tourpak detachable and already moved back that the front end of the bike is already lighter so adding his kit and moving it back farther will make the center of gravity move back farther. After making the tourpak detachable I had enough space so I did not purchase Georges kit.
Do you have a stock seat - the stock seats also puts the rider up on the tank more. After I bought my corbin it moved me back.
One accessory you gotta get is the Hawg-Wired system from Hd-dude. It is UNBELIEVABLE and worth every penny! Then you will have your 4 speakers up front. One of the best upgrades I have done.