i have a '94 LS400 with these issues.....white smoke, exhaust leak near engine, kinda loud at times.....maybe the egr tube is the culprit! i did plug the ACV on the power steering pump which cut back the white smoke CONSIDERATELY, so i get some but not alot of white smoke on startup.....
It should be "corrugated" or - have an accordion bend in it to absorb the vibrations and allow for expansion/contraction due to temperature changes. I just don't know why they did not go with a flexible steel hose, like some guy did it... there is a write-up somewhere on the net, he just used off the shelf stuff from home-depot and made his own new steel hose that he fit in the ends of the old EGR pipe and it worked.
actually if you read that thread, the OP never said it worked in the long run. i believe it will work initially but over time the heat will destroy the gas line which he retrofitted. it was never mean to withstand heat.
my EGR tube has the accordian flaps, as they all should!