At 133K km (about 83K miles), my 2001 Boxster S has had the waterpump replaced at least twice, I just replaced the reservoir tank, but I'm still on the original cap (I keep forgetting to order a new one). So far no issues with this cap.
^ If you removed that old cap more than a few times it's probably holding less pressure each time than if you left it alone.
Some of our professional mechanics here say it needs to be at least 18 PSIG or they are tossed.
That's tough to tell from merely a visual inspection.
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GT3 Recaro Seats - Boxster Red
GT3 Aero / Carrera 18" 5 spoke / Potenza RE-11
Fabspeed Headers & Noise Maker
BORN: March 2000 - FINLAND
IMS#1 REPLACED: April 2010 - NEW JERSEY -- LNE DUAL ROW
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