Don't worry about the change to 134. It is not widly known that 134a needs more pressure and really isn't very efficient either. Switch over to hydrocarbons. These refrigerants are much more efficient, you only use about 1/2 the amount that is in there now,it works with less pressure and you will get better gas mileage when you use it. Here is another plus, most all the seepers, you know, the ones that need charging every year, will never need charging again because the molicules are much larger and they won't leak. I put it in my 88 240 and I don't run my system on high anymore. Last summer I drove from Pa. to Wa. and on the way home, going through So. Dakota, it was 117 degrees and we had the air on low and the thermostat wasn't even all the way up and we were cool and comfortable. It also is very cheep and is envirmentally safe too. To charge your car it will cost you only about ten bucks or less. Take out the freon and put this in, there are no changes to be made. Anyone can get it, there are no lisences or permits needed. Do it yourself and save.