R134a is not all that bad....If it's done properly. If the system is flushed with a special A/C solvent that removes all the old R12 oil and an automatic adusting Orifice tube is installed (along with all new rubber seals) then the R134a should cool off very well. If you want it even colder then you would need to have a larger evaporater made and installed. IMHO...I would go with R134a. It seems that if you go with either R12 or R134a your risking something. R12 you risk getting a mixed blend of propane and R12 or the mechanic doing a botch job in recharging it...R134a you risk not having it cool properly and also risk having the mechanic doing a botch job. I have to recharge my system at some point (after it's on the road) and I'm going to use R134a and do it myself...I have a friend of mine that's an A/C tech that will vaccum out the system for me. I might even have a larger evaporator installed...I know of a place that custom makes them. Steve