Merv, the first PDR cooler I tested and still have is a little different than the current one, current one will be better, but on mine as you may remember I did a write up on the board. Air temp drop at the hat is 60-70 degrees but I always say 60 to be safe, no I didn't dyno before and after but I have read that the stock cooler is an 8 psi drop across at 60+ boost levels, this one is 1 psi at 30, 2 at 40 and 4 at 60, it made as much difference at the hat in air temp drop as the water injection did using the stock cooler. There cheap enough that it's foolish not to buy one over a stocker and yes I think they are well worth it, Piers doesn't pressure them to 500 psi as there is no need but does test them to 125-150 then heats them up to simulate the hot air going into them.
Jim