Gearing question?

On my revo 3.3 i am experimenting with different gear ratio's and I'm reading a lot on it and am reading a lot of different facts on gearing. I am trying to gear my revo for more acceleration and switched from the stock 38 tooth spur to a 40 tooth which did help but wasn't enough so do I need to go from a 15 tooth cb to a 14 tooth cb or go to a 18 tooth cb for more bottom end. Each forum I read is different and some say go down on the cb and some say go up not real sure which is correct. In my opnion I would think if I go down on the cb it will give me more bottom end but I'm not sure and cb aren't cheap so I really don't want to buy a bunch of different one's to figure it out. Any info will be helpful. Thanks