tricky-tricky at least IMHO.
One cylinder always ever so slightly robs the other of the fresh charge. There also will be air-fuel mixture ratio differences between cylinders. Because of that, different heat range spark plugs I believe in, not different header lengths, unless the canister is completely indifferent of the used length.
You might argue that the different EGT (exhaust gas temperatures) justify header length adjustments, but I think that is academic, and the effect is too small for the runofthemill user to notice.
With the above scetched problem at hand, using the headers to get a wider power band even sets the cylinder power output further away from each other. This will make the engine run rough, and it looses the top end power as well.
Most flyiers even now have difficulty in setting up a tuned system. Tuning each cylinder seperately is more complicated and requires each cylinder to be run with the other non-active. This again will influence the gas transfer of the non-active cylinder.
All in all, I believe the outcome will be very uncertain. For someone to try his hand, a real challenge though.