Not sure. They aren't very big. If you were to ever upgrade you might need to get a new master cylinder. I've been doing some research on my own and I have found that the wilwood superlite 3 may be one of the few options we have for the Protege, that is, if you were planing on upgrading
yeah i am planning on upgrading to AP Racing calipers and rotors....i'm going to have to get the abs adjusted to suit the new set up, but i was just curious of the stock piston size