I am far from being an expert here, but I have two Tigers. Both S&S, one with metal gears and one with plastic. Are you running with metal gears now, or planning to add them? I only ask because from what I've read, if you add the bigger motors you run the chance of overheating and blowing your circuit boards. My metal geared Tiger runs much better in grass than the plastic gear tank and I can only assume that it is because of the added weight. I'll say this, if I bought the plastic geared tank first, I would not have bought a second one. There is that much of a difference... and as you will read here, metal tracks only improve it that much more but I'm still saving my pennies for those.

Oh, I forgot, you said yours is non S&S... different circuit boards. You may want to upgrade there as well for the proportional speed control the S&S boards offer.