Upgraded motor & transmission mounts stop the drivetrain from acting as a pendulum during braking, acceleration and cornering weight transfers.
Solid shifter bushings stiffen up the throw of the shift arm on top of the transmission and at the base of gear selector.
A 15-25% short shifter is also a nice touch.
I have found this setup to be sufficiently stiff for most performance driving, but I do see the added benefit of reduced reach with the CAE, Coolerworks or WK shifters, which will reduce shifting times. Though, I personally already shift too fast for the DMF with revhang turned off.