Since I've started light testing with c&p mostly for kicks mostly, that's exactly the results I've found. Unsurprisingly no light seen. As for the flat spring's reliability, I'm completely confident in the long time Purolator design. And I default to
@AuthorEditor original testing of the flat spring design
HERE. Also, there's no way to know precisely when or how much the valve opens in situ real world use. Afaik, member Jim Allen testing with gauges is the only one that has been able to give some idea when bypass occurs. Anything beyond that 'I' classify with the WC Fields saying, "If you can't dazzle them with brilliance........."