i did a rear disk swap on my dx hatch with some stainless steel lines also, should i upgrade the master cylender witha DA?

 

A DA 15/16" MC??? That will require you to cut one of your hard brake line fittings and then reflare the line with the properly sized Integra fitting. You will also have to swap out your stock brake booster for the Integra one becasue the Integra MC won't work on your stock booster. Booster isn't much fun to replace.

The MC from the 90/91 Civic Sedan EX is 15/16" and will bolt directly onto your stock booster. No line mods and no booster replacement.

 

You can switch over the both the master cylinder and booster from the 90-91 Civic EX 4dr. without a problem.