Stang,
Stick with one change at a time.
Start with the FMF suggestions and we'll go from there.
The only change you will need to make is put in the 158 main. The Bel Ray Oil ratio is the same, pilot air screw etc.
You can run any mix ratio you want and still have a good running bike.
Patience Grass Hoppa.. I know how hard it is to just keep the changes slow and one at a time. This will pay off in the long run.
Take your time swapping out the main through the bottom of the carb so as not to cross or strip the threads, it really isn't so bad. You will need a small (1/4" drive) 6mm socket or jet wrench.
Here is a trick motion pro:
http://www.motionpro.com/motorcycle/partno/08-0023/ Craftsman socket :http://www.craftsman.com/shc/s/p_10155_12602_00934602000P
No worries yet Matey!
Yes also on the rich to lean direction. Why take a big chance on ring, Or Worse piston seize.
I don't want you to feel like I'm yelling or you're in the principals office. Consider my suggestions and weigh them against what you have read in your clymer and what the recommended jetting specs from the pipe manufacturers are.
There really is no magic #'s as the variables are always different and changing.
Weather,elevation,wear and tear on the equipment etc. Once we get you either to a point you happy with the performance, the only changes you will have to make jetting wise to stay in the ballpark is winter summer main jet. an 8 minute process at most.
The more critical you are with performance the more changes you will have to make.
As an example a Mechanic may change jetting on the bike he's responsible for through out the day as the relative humidity,temperature and track conditions change from morning 'till evening.
Tuck\o/