Dan,
I'm not saying Peel and Seal is better,,,,, just cheaper!!!
the B-Quiet Extreme web site "claims" 230*,,,it failed at 160* on this test!!!:
http://www.sounddeadenershowdown.com/heat/
which is the approx same failure temp range as Peel and Seal, (has to stay stable at 158* for 8 days or something like that to pass roofing codes)
both are 45mils thick so I'm skeptical about the B-Quiet minus 67* temp rating claim as well....
I have read before and again in that article link that MFM Building Products Mfg. does make several of the "auto" sound deadener brands....
(maybe even B-Quiet?)
the "Peel and Seal" product name is for MFM's roofing products "line" for the past 20? years
use any brand you like....