The tow package includes a heavy duty radiator and heavy duty alternator....maybe not a bunch of weight, but I think those are in the FRONT of the vehicle. ;)
The 2011 is louder than past models IMO, but I'm being told the towing package has little to nothing to do with that.
Lexus doesn't include the trailer hitch on a towing package - it is just tow ready and has the capacity.
Thanks though!