Brandt,
You guys going to make it up this weekend?
I've been playing with the F brushes too. I've been seeing some really good numbers on the dyno.
I've been liking the red/green combo for both 4 cell 12th and 6 cell touring. The only difference is I will slightly tweak the touring green spring just a hair more. This goes for stock and 19 both.
I agree with EA and Brandt the best for touring I've found so far for most motors is narrowed slightly with a thin vertical slot. I used the red/green combo stated above. Also stock and 19...
On 12th I run the brushes full width with a vertical slot...
I've also tried slightly narrowed with a 3/32" hole and red/green springs on a couple peak dynasty 19's. They seem to like this combo.
On the Reedy QM's it still seems to favor the full width and 3/32" hole with the F brush. I use green/green springs with the positive tweaked a little more. (remember with the fat comms you have to spring down b/c the comm is bigger in order to achieve the same tension as on a reg. comm motor.)
Here is the what I've noticed.
Vertical slot seems to add torque w/o hurting the rpm.
3/32" hole seems to add even more torque, but you sacrifice some rpm.
Narrowing the brush reduces rpm and adds torque.
The biggest advantage I see to narrowing the brush is that it allows the motors to run cooler in 6 cell applications especially touring car. Less heat = more power...
$.02