I don't know if the upper mount affords you a shifting benefit (i think
probably not).  Flushing or bleeding the clutch is the same procedure as
bleeding the brakes.  To flush the clutch, get a clear tube from your local
auto parts store that fits around the bleeder valve (3/8" i think) it should
be about 24" long or so.  The bleeder valve is easy to get to through the
top, it is located right next to / below the shifter weight ontop of the
transaxle.  Get some of the same brake fluid you use for your brakes, as
both the clutch and brakes use the same fluid resevoir.  remove the dust cap
on the bleeder valve and place the clear tube over the valve (this should be
a snug fit).  Place a clean glass jar under the car just behind the driver
side CV axle.Run the other end of the hose into the glass jar.

Put about 1" of clean brake fluid into the jar to prevent air from being sucked back into the line. Tape a socket to the end of the hose in the jar. The socket will weigh down the hose's tip and make sure it's always submerged.
[ aqn ]

  Remove the
fluid resevoir cap.  open the bleeder valve approx. 1/2 of a turn (180
degrees or so).  Fluid should start slowly running through the clear tube.
You can push the clutch pedal slowly a few times then check and add fluid as
needed.  The clutch system doesnt use much fluid so a few pumps should do
it.  check the color of the fluid to see if it is contaminated.  It might be
a good idea to have a friend (armed with a beer of course) to help so one
can pump the clutch and the other can watch the clear tube to see if any air
bubbles come out.  After the fluid color changes to the color of your new
fluid, you are done.  Tighten the bleeder valve (do not over tighten).
Remove the clear tube.  top off the resevoir.  Replace the resevoir cap and
the bleeder valve dust cap.  If this doesn't solve the problem, then no harm
done since this procedure should be done every 2 years +/-.

I hope this helps

Gavin