Problems with 2005 Honda Pilot CHILD SEAT

I purchased a radian 80sl in february of this year (seat dom- 1/2010, superlatch belt dom- 12/2009) and installed it right away. it was installed with the superlatch belt and with much less than 1" of movement when checked at the belt path. a few weeks ago i noticed that the tilt lock adjuster on the superlatch belt had moved further down on the seat. i checked for movement at the belt path and it was a good 2"+ of movement. since then i was needing to tighten it everyday, however i have stopped using it altogether since my 2 year old is able to push the release on the superlatch belt and loosen the seat even more. i also noticed that the seat gradually reclined greater than 45 degrees on its own (i assume this is due to the superlatch loosening). (related vehicle information: model year=2005, make=honda, model=pilot). *tr

I have been told that the britax regent was crash tested with the tether. i am have also been told that the tether in most cars only holds 40 lbs. how then can my 80lb child be secured in the britax regent if the tether can only hold 40 lbs.? (related vehicle information: model year=2005, make=honda, model=pilot). *tr