Can you narrow your factory gas tank?

[SS1156]

I was wondering if it's possible to have your factory gas tank narrowed? I was looking at the BMR Torque Arm kit and there are some photos posted of the kit installed. I noticed that there isn't much room for the tailpipe where it goes around the tank. I think if you were to narrow the tank you could get a 3" tailpipe through there. Check out the thread on 2nd Gen rear suspension in the "suspension" area.