Precise Flight speedbrakes were installed on the aircraft to reduce shock engine cooling and allow for accelerated descents without decreasing engine power.
I can't speak for the APS guys, but can say I have a set of those, plus a set of intake plugs that automatically block the intakes if I fly into rain. If accelerated descents create shock cooling, imagine what happens if you fly into rain!
Along with the Turbo Encabulator to scavenge lead while I'm idling the engine for 5 minutes to cool the turbo, I've purchased just about every useless piece of expensive crap to deal with just about every non-existent problem imaginable!