I remember watching mine at 21psi on the dyno and it was rock solid, but that was nearly 4 years ago. Been running 19psi since and it seems ok, I'm not able to peek under the bonnet while someone gives it a bootfull, it will never replicate boosting under load. But yes rubber does lose it's hardness just like we do with age lol, it probably would be worth doing after a few years.