I just installed some rear disk brakes on my 1994 Honda Civic EX Coupe. I got a new proportioning valve from a 1995 Honda Civic SI and a new brake master cylinder from a Civic SI. I also have some Earl's Steel Braided lines. I have new brake pads and had the rotors resurfaced. When I completed the install I bled my brakes. For some reason my brake pedal is still spongy to the touch. I checked the rear disks and they are clamping and checked all the brake lines and there is no air in the lines. I was wondering if you can provide me with some suggestions as to how I can remedy this.

My initial thought was because I didn't replace my brake booster but I checked online and saw that the brake booster for a Civic SI and a Civic EX are exactly the same. Please let me know if I am wrong.

Thanks in advance for your help!