I wouldnt imagine that a pressure regulator would truely have a vehicle specific restriction but im also not an engineer. the two im looking between is the aem 25-300 and 25-3001. anyone know the difference?

 

Civic 1989-91 Si 25-303
Civic 1990-91 EX 25-303
Civic 1992-94 All 25-300
Civic 1995 All 25-300
Civic 1996-00 DX/CX/LX/EX Only 25-301
Civic 1999-00 Si 25-300

 

ya i know that difference but im talking about how it actually functions. thats what i dont understand.

 

because the regulators bolt on to the factory fuel rail, they are application specific. There are slight variences in fuel rails through the years and models, this causes a new regulator to be designed for each app.
There is a universal regulator that is available that does not bolt to the fuel rail (remote mount) 25-302 that will work with any fuel system with a little plumbing.
hope that helps.

 

There should be know differences in function, I would imagine the 25-300 and 25-3001 are the exact same.

If there is a difference it is the design of the fuel return line being at a 90 deg or straight angle or the base being offset or straight. There should be no differences in function.