For me it was very noticeable. I spool up faster. Boost targets are hit more precisely. Boost curve is much smoother and my timing looks sport on.
19.4psi is the highest I ever saw a log go pre ISO. With ISO i haven't pushed it over 18 since I am on snows now and it just gets a little hairy. I think you should go do a few logs. Start at map5 with no meth... then go +4 ad and work up... compare to your old ones.
For me the best improvement is the way the turbo will initially respond when you go WOT. Hard, smooth, and accurate.