Ara (shay2nak) --
Per the instructions that came with the new thermostat (A. C. Thermostat Kit, p/n A120P0149S), that I had installed in my 2005 Elise, "The electronic thermostat was introduced on factory build at approx. February 2007".
I think the new thermostat (along with switching to the "Hose, heater to plenum, insulated", p/n A124P0025F) made a big difference. This updated hose was fitted started with the '07 model year and can be retrofitted to the earlier cars.
I have not looked into using the "Hose Insulation Sleeve, heater to plenum", p/n A120P0161F that was apparently fitted to the "Gulf states" cars. If anyone has, how well did i work?