Im about to take my frame down to get blasted and asked the guy about por-15...
His opinion: it's crap. too expensive, doesn't do what it claims... much better products on the market.
Unfortuneately I didn't have time to go into details with him on the phone the other day, but certainly plan to when I see him soon...
Just thought I'd pass along his comment. he's been blasting cars for many years...
my .02