the gun without modding has the yellow barrel which moves around so you can shoot at a 90 degree angle.

then open the gun up and the first thing you can do is pull the barrel out. (it came out without any problem for me)
http://i363.photobuc...ds/P1000674.jpg
(you can see the gears here, they are white.
next I improved the seal on the plunger rod by using craft foam which i just pulled off of a big bad bow arrow. i used one of the fins. then i taped it on with masking tape.

http://i363.photobuc...ds/P1000678.jpg
then to get the new barrel i used 1/2 inch cpvc which i love because i can get 20 ft for about 3 bucks but to insert the barrel i had to dremel out some of the shell.
http://i363.photobuc...ds/P1000679.jpg
put the gun back together and voila! you just got a gun that can get 60 regularly.
http://i363.photobuc...ds/P1000886.jpg
ps: i forgot to mention, if your barrel doesn't fit duct tape fixes everything.
have fun