what is it that you want to gain from your gear change? that is what you must ask when considering a change. if you go smaller on the bottom and larger on the top like you have stated, most likely you are going to get more top end and lose a bit on the hole shot. i personaly like big gears on the bottom and then gear the top to match. but it all depends on what you are doing with the sled...every sled acts different to gearing changes and i think the nytro having as much low end grunt as it does could pull some serious gearing.