To answer your original question, Twin NDB, Some of the W/M systems I have used are worth their weight in gold. On TPE 331 -3 and -10 installations, the published torque increase was 15%, enough to boost RTOWs by 500 lbs on warm days on short gravel strips. The actual W/M weight carried was less than 60 lbs. (one firing) On TPE 331 - 11 Metro III installations, the RTOW could ideally be boosted by over 1000 lbs on paved runways just under 4000 feet while conforming to ASDA, TODA, and TORA limitations. (climb performance was never an issue when wet) The minimum quantity for such an exercise would be about 60-80 lbs, and torque increase about 20%. Firing several times per day in summer for a few years and never seen a system failure, Reliability was good. Just one problem, very abrupt. The Dart 534-2 (I think) had a much smoother power increase/decrease due to slowly opening/closing injector metering units.