A stock D-5 converter is a great part. On my original GN I have run a stock converter to 11.38 @ 120.25 mph (locking it up) and on my other GN I have run 13.25 @ 102.95 mph and I have quick spool up on both cars. On the 11.38 car I have a TE-44 turbo and a front mount, on the 13.25 car I have a stock turbo and a stock intercooler.
I have also ran an Art Carr 9" converter and it is almost impossible to launch with true street tires because it brings in the power way too quick. If you are running slicks a 9 or 9.5" lockup torque converter will probably lower your ET's as long as you can lock it up. If you are running street tires you might want to try a stock or modified stock converter to soften the bottom end.
Good luck,