Found an interesting item from TRD Europe. Look at the dual exhaust, very cool. This is pure for look and sound with very little if not ZERO performance gain.

http://www.tte.de/popup/cm_lexus_RX300_XU3_silencer.htm

Notice that this is for RX300 (not the first Gen, but in Asia and Europe they don't have our 3.3L engine, probably due to registration cost as their registration fee is based on displacement). However, TRD Japan has a different rear muffler for both the RX300 and RX400h (same part number), so I assume that this part will fit on the RX400h, and very likely the 330 too.