The torque rating on my '97 540iA is 440Nm (325lbs-ft). That figure is according to the manufacturer, ZF. The tranny model is A55 440Z 5HP24.
Both ESS and Dinan offer superchargers that produce over 400 lbs-ft of torque.
Assuming that I install a blower, isn't this set-up detrimental to the auto tranny?