more bottom end torque???

how can I get more bottom end power? should I go 1 tooth down on the front or like 3 or 4 bigger on the rear? what is the diff. I do alot of tight trails and rocky trails. I dont need any top end power. I hope some one can help. thanks. I'm running a 07 400ex hmf slip on,jetted, uni filter,1'' holes in air box lid, snorkle removed.:icon_ rocker: