I have gathered the following information from over on DTR so correct me where I am wrong:
The maximum pressure to a Bosch VE pump should not exceed 20 psi for any extended duration or the VE pump will encounter seal related leaks.
The lower pressure piston lift pumps are regulated to 15 psi maximum output.
The only physical difference between the lower pressure and second generation higher pressure lift pumps is the ones for the second generation are set at 30 psi by incorporating a longer length pressure relief spring.
So the question is why can't we take a high pressure lift pump that is sold through most auto parts stores and trim the pressure relief spring to get the lower pressure that we can use with the VE pump?