The Me410B-2/U2 top speed is listed at 388 mph with cruise at 325. Armed with 4xMG151/20 and 4xMG131 of which 2 were mounted in the barbettes.
The Me410B-2/U4 top speed is listed at 370 mph, cruise at 325 still. Armament identical except for the removal of two MG151/20 in favor of the Bk5.
Both types are powered by the DB603L and the B-2/U2 was a few mph faster than the B-2/R types, the R5 doing 380 and R3 386.
As a comparison, the Me410A-1 max speed was 375 mph and cruise 315, powered by the DB603A.
I'm unable to verify the above data so if anyone believe they have more accurate figures or access to original test data please correct as needed.
B-2 types forward armament:
R3 - MG151/20 x 2, MK103 x 2, MG131 x 2
R5 - MG151/20 x 6, MG131 x 2
U2 - MG151/20 x 4, MG131 x 2
U4 - MG151/20 x 2, MG131 x 2, Bk5
Personally I would think the R5 to be the most useful bomber killer but in AH who knows?