i converted my1973 camaro with a march serpitine pully with new style ac compresser for r134, i installed a aftermarket poa valve with a pressure senser (it has no valve or spring in side? ) had new hoses made and new expansion valve. I flushed the condenser out and the evaperater. A frend pulled a vacume test and charged it with 1.75 r134 the low side was at 50 so he didnt want to add more it didnt cool well so i added more myself from a can the pressure came down and it started to cool better?. when i was finished the gauge went up to 55 but it held about 16 oz more temp outside was 95 f. i drove the car with my gauge in vent itcooled to 60 f. how high is to high on low side and do you think i can do better out the vent. i heard the condensers are differant i can see the differance by compairing it to a newer one will this help . i replaced the dryer. it is a high performance engine 427 stroker small block the engine runs cool but the under hood temp is high from the headers is this hurting me and can tinting the windows help i am running electric fans (pullers)