Who had the most successful Modified Production car?

[Dwight Southerland]

IIRC Ridgeway actually marketed his first, so you could say he had the first commercially available. Edelbrock had the name recognition and national marketing exposure so they quickly became the source for them. Who knows the first homemade ram type manifold for the SBC. The Ramchargers were the first to heavily pursue the ram wave theory in intake and exhaust for drag racing application.