From LEMB, which doesn't let you in unless you have login for the forum, so I will post it here....
In a discussion regarding Me410 performance, and replying to a question about the impact of different loadouts:
"There are figures for just this given in Mankau/Petrick, near the end of the book.
BK5 listed as 15kph penalty, 2x 3x WG21 : 20 kph. Abwurfanlange Mittelflugel - 4 x SC 50 od. 4 x BL-Bomben : 25 kph. Both 2x300L and 2x900L drop tank configurations : 25 kph. The external MG151 pod isn't listed, and doesn't show up in Stocker/Petrick either, so it was possibly one of those field-mods. The pod itself looks like the one that some late Fw190A's used. Might be the very same type."
He says 2x 3 WGR21, so I don't know if he's confusing the 3x WGR15 test configuration, or if he means the 2x 2 configuration they really used. It would be easy enough to compare to Me110 drag. It should be identical to that, because it was 110 units that adopted it to the 410 from their old airframes.
Related note: Does anybody know what the records say for the Fw190A's underwing WB151 pod? How much drag does that add (as in how many MPH are lost)?