Jinx I think a 20-40 horsepower is very possiable. Can you put your hand in the muffler and feel the glass pack? The exhaust has on most cars a glass pack inside. REMEMBER you need a 11/2 of back pressure to help the motor get max performance. There used to be a guy that built cobra exhaust in the Shelby club. It looked prefect to the orginials. Dynomax and flowmasters make the muffler you are looking for. How are your side pipes put together? Flange, slip joint, or clamped? Hope this puts you in the right direction. Rick Lake ps SAVE the other pipes for the street drives, or the COPS will have ticket partys with you.
