measuring with wrap on

I tried, just for the hell of it, to measure myself after my second set today. I measured my flacid size with my hanging wrap on(not the hanger too,though), and pulled out(BPFSL with my wrap on). What I saw was almost 8 inches, if not there. My question is-would this be an accurate gain, or would you usually measure longer this way than a normal BPFSL?