Don 
2006 Toyota Tundra Access Cab SR5 4dr Access Cab SB (4.0L 6cyl 5A)
exhaust leak 06 tundra
 At 16,000 miles I heard a exhaust leak, more pronounced when the vehicle was cold.  Sound like defective catylitic convertor issue. I have had it back 2 times at the same dealer I purchased it from they said on the second trip back, could I leave it for 24 hrs so they could test it to which I said yes.  When I dropped it off I put a penny over the front tire. 24 hrs later they called me, stating they could not find anything.  Guess what when I picked the truck back up it was in the same parking spot with the penney over the tire.  What a test.  If this is not corrected, my toyota buying days are over.  My friend is a cheif mechanic at a gm dealer and agrees it has a exhaust issue.