I live in Alberta and have tried almost every setting to get a clean tank sample and retain some capacity in spring wheat. We tried small wire concaves, large wire concaves, every possible combination of cover plates under the concaves and fooled with the plates that cover the separator grates and there was no one adjustment that made much difference. I saw NO noticable difference from tank sample with the concave cover plates. After using them for a couple of days I took them all out after trying different combinations and it did not affect the tank sample. The wide wire concaves were somewhat worse than the narrow wire, but not noticable enough to bother buying and installing a set. Setting the feed accelerator to slow speed helped somewhat. The belief is that some of the heads have the white caps broken off by the feed accelerator and then not threshed out properly at the concave. In extremely dry wheat straw, where the grain moisture was 10-11%, we found that we were overthreshing the straw and severly overloading the outsides of the cleaning shoe and putting almost no material down the center of the shoe at all. This caused a lot of the white caps in my sample as the shoe could not do as good a job. Installing the coverplates in the separator helped to even out the shoe load and cut grain losses. I would open my concave to 10, slow the rotor to 850 in the heat of the day and install the separator plates if you are doing very dry wheat straw. By doing the adjustments we saw our productivity go from 700-800 bu_hr to 1000-1100 bu_hr. Take your sample with the whitecaps to the grain elevator and have them do a dockage for you. I think you will be surprised how little impact the whitecaps will have on the sample. Beware that high rotor speeds and tight concaves will have lots of cracked and broken kernals in the grain tank, which causes large dockage numbers. The bullet rotor does not seem to be any better than the original rotor for whitecaps in the grain tank.