What gearing you got? .15 or 2.5? Got any aluminum on it besides the bottom plate?

Anyway I did the same thing on my 2.5. except I put the pack inside my shock tower & zip tied it. I got the dirt hog tires on a full aluminum suspension with a-arms extended front & rear and a 1/4" longer. I got no troubles! I also run big bore shocks in the rear with a 7.2lb spring for a savage. I got the x-tra firm rear springs I had on the back & put them up front on a stock plastic shock. Some fine tuning and it should tear it up!

Try putting either the pack back where you found it then add weight or change to a higher gear ratio! If none of this works than keep your finger off the trigger.

DIGEEDOE