Firming up a non-Sport LS460

One of my clients, a long-time Mercedes SL driver, recently got his first Lexus, a 2010 LS460 sedan without the Sport adjustable air suspension.

He likes everything about the car except the "floaty" ride. He doesn't have the feeling of control and response through the pillowy suspension. I suggested that his hands and butt will recalibrate to the fainter signals but he's covered 6.000 miles already. I suggested he try putting an extra five pounds of air in the tires for a start.

Does TRD, Daizen or some other tuner source offer stiffer bushings, shocks and/or sway bars for these big sedans? Or are such parts available for the Japanese-market Toyota-branded versions of the LS460?

Thanks for your help!