The build quality
in the cockpit is much better today (on the DA42 - not looked inside a DA40 recently) than it was in 2002.
I am still not a great fan of what looks like zinc plated fixing brackets and zinc plated DIY-shop nuts. This stuff will rust fast and, according to an owner I spoke to recently, it does rust fast and some of gets replaced at every service. Still, not a lot to moan about and they can address detail like that easily. But then I am spoilt, with the super build quality, finish and general engineering of a TB20GT...
A 170HP engine on a DA50 will make it an absolute pig. I can't believe they will really do that. That plane is built for four fat Americans (or, these days, four fat Brits or Germans).
"200kt" could mean a lot of things. To pull 200kt
IAS, the DA50 would need about 400-450HP. Even the Grob 140 (a dead project
AFAIK) with a 450HP Allison turbine didn't go faster than that and that was a smaller cockpit than the DA50.
However, 200kt
TAS at 25,000ft is
136kt IAS (ISA). You could build a 750kg plane powered by a lawn mower (Rotax) engine which would do that. A turbo-normalised TB20 (250HP) that could pull a sea level MP at 25,000ft would easily beat that at 65% power; most turbo planes can't because the MP is maintained only to about 15,000ft. The TB20 needs about 65% power (160HP) to pull 140kt IAS and I guess the DA50 (bigger frontal area, fixed gear) could pull 140kt IAS with maybe 200HP, so a 300HP turbo-normalised Lyco, or a 200-250HP turbocharged diesel could easily get you 200kt TAS.
With a decent turbo,
200kt TAS at 25,000ft is easy to achieve and that is exactly how Columbia and Mooney get their impressive sales brochure/advert figures. They are betting on most of their customers not knowing TAS from IAS. Of course the fuel flow is "appropriate" too
The oxygen flow rate for four people, in these unpressurised planes, at 25,000ft, would be eye watering even with the Mountain High electronic demand regulators. You have to use masks, not cannulas, and in the end this does not represent any kind of practical mission capability.