I have decided on the basis of a couple of test flights that the mods are not for me.  I simply cannot get to 35,000 feet with them, where I can without them.  Furthermore, EPR settings did not seem to be giving me the desired cruise speed.  With all due respect to the people who put hard work into them, I'm not sure they result in a net improvement for me.  I'm going back to the by-guess-by-golly flying where I can at least hold altitude.