We have a 2002 Xterra SE with the Super Charger.  For the first
couple of years that we owned this vehicle, it had lots of power and
I would never have to downshift to get up a steep hill.  For the last
two years, the power seems to be gone.  I have to downshift on steep
hills.  Under heavy towing loads I have to downshift on even small
hills.  I've had the vehicle in the garage to be checked out several
times and they keep saying nothing is wrong.  I'm posting this now
because I made a drive yesterday that involved several steep hills
and got reminded again just how much power the Xterra has lost since
it was new.  The lack of power isn't really very noticeable driving
around the city or on flat roads.  I'm wondering if the problem could
be the supercharger?  If the supercharger were not operating
properly, would the driver be able to tell?  Would the symptoms be
what I'm experiencing?  Is it possible that a bad supercharger might
not have been detected by the Nissan dealer on those occasions that I
have had the Xterra in for this lose of power problem? The dealer has
never found anything wrong.  They say everything is OK but I know
it's not.  The 5-yr extended warranty will soon expire.  That's
another reason for me posting now.  Any and all advice/comments
appreciated.