When my rear air bags burst I changed front and rear air suspension to coilovers, three of them leaked within a short time. Refitted the front air shocks and got Lexus
shocks and springs for the rear. Car handles great.
I found nobody doing bars for Lexus. I had to buy from Lexus for a ls400 (still have them ) and my present ls430. The 430 bars are a p i t .. to fit compared to the 400.
If l listed all the failures in my LS430 it would probably put you off the car but that is the luck of the draw. My 2 previous 400's gave very little trouble.