After driving a battery pack out in the Pershing, I think the gears are finally starting the break in properly. The tank is noticeably slower, and slightly pulls to the left -- but nothing I can't live with. I guess the metal gears and sprockets do add a lot of rotating mass to the drive train, making speed suffer. I know everyone on here wants a slower tank, but slower due to heavier rotating weight I think will reduce torque as well. I may have to look in to going with a 7 cell battery -- especially if I go with metal tracks eventually. I'm happy that the tank is fine with the upgrades now, but I'm pretty disappointed with the installation-ease (or lack thereof) of the hop-up parts (of course, we are talking about cheap tanks here to begin with). All of driving so far with the new upgrades has been inside -- I'm anxious to see if it still has enough go-go power to climb like it did before.