[Grants911]

Thank-you everyone. Here's my current thinking, please weigh in with your thoughts.

I will replace the small, early model year, 964-355-025-52, part number master cylinder with a new more common part # 964.355.903.00. That will give me an upgrade from the 20.6mm bore to a 23mm bore. Going the 993 route is a great option but more than I need, especially given the extra steps required to make the parts work in the car.

My final question to all of you;
Will part # 964.355.903.00 simply bolt on to the brake booster in place of the older 964-355-025-52 part that’s in the car without any modifications?

And some have suggested that I have the the bias valve removed at the same time… thoughts on this?

Thank-you for all your help & experience.