Right.If you are using the desert pipe, you would be best advised to move it to the right hand mark,( anti clockwise).Your train of thought is correct, but what retarding(R hand mark) does is moves the combustion process back, which enables more heat to pass into the pipe, raising the temp.The increase in temp means the waves in the pipe can move faster and gives a more pronounced effect in the top end of the 'band.
OR, by advancing the ignition, (L hand mark), you give the cylinder more time to have the mixture burn enabling a greater pressure rise in the cylinder, but having increased the spark lead time, you get increased pumping losses at high rpm.
If you move yours left, you will not have pipe and ignition in sync, and will lose some of the benefit of having the desert pipe. As long as you stay within the marks, have a play and then ride it and see what suits you best. Ultimately though, if you want fat bottom end, I would change the pipe to a Gnarley woods pipe. part no 020055.HTH.K.