OK here is an update on my killer chiller system for anyone interested?
After lots of trial & error it is working fine.
It seems that the ideal amount of refrigerant is 2 x 12 oz cans of 134a. NOTE USE 134A ONLY!
My system runs at idle or just city driving about 20 degrees Fahrenheit cooler that outside temp.
So on a 80 degree day my ait is approx 60 degrees. I have a flexilite fan installed in front of my condenser & that really helps when sitting in line at the track.
Other cars have gotten cooler ait & I think that is because my system has quite long runs. I have insulated all the plumbing as best as I can, but their is still heat soak from ambient sources. Everything is hidden & the tech guys have not even noticed it.
Didnt run any faster times with it, but the track days I have gone to had some very hi outside temps as we are having the hottest summer on record.

Barry