I'll tell ya, my Turbonetics T66 single BB is currently being driven with a stock D5 converter, drives fine and only has a very slight amount more lag than my TE44 which came off. 0-30 from dead idle at the same boost its only 2 tenths behind. I haven't even yet bothered to put in the ArtCarr 3000-3200 L/U that I have waiting.
I'm up to 20 psi in 1st/2nd and 18 higher on 93 octane with 20/18 timing and its running 3-6 tenths faster from 0-80 than the 44 at 17 psi which I could never run higher boost than that w/ no knock. Hopefully the gains will be even better in the higher MPH's. Changes were the T66 and 60 injectors so somethings working better for sure.
You should go bigger w/ the converter you have IMO.
HTH