What is the estimated HP of a /6 after the Clifford Intake and Headers? Would I have to change the carb if I bought the intake. Thanks.

You have to have a 4 barrel or 2 barrel carb for that intake. If you choose 2 barrel you get the two barrel adapter plate, and likewise for the 4 barrel. They do not make a 1 barrel plate for their manifolds.

Clifford claims a 25% increase over stock by using their intake and headers, along with a Holley 390 or Edelbrock 500 carb. I'd say this is fairly accurate. I could feel a big seat of the pants difference in power, throttle response and driveablity when I put these parts on my otherwise stock 225 in my D150.

Ron