I have to agree that the DRZ400 is a lot more fun than the street bikes I've owned. I've had my 2005 since Feb 06 and have had a lot of great rides, most of them dual sport vs street rides
I would like to know what riders have run into when mounting their after market tanks. I read one post that "massaged the tank into place." I purchased a 4 gal IMS tank that I am very pleased with now. Installation was a bitch. Not wanting to put stress on the radiator at the shroud mounting points, I made offset brackets - the bolt holes were off by 1/4 inch. On the rear mounts I altered one bracket and lined up the holes by pushing the tank forward with a lever. Are they all this difficult?
On another note, I found that the Acerbis locking gas cap works on the IMS tank - may be old news, but feels better when taking long trips and leaving the bike unattended.