Going back to the original question the m.p. one makes way more power than an original or the A&A. It is basicly a copy of the Ray Barton Cast one that he had for years. They are taller so sometimes fitting under hood with air cleaners may be a problem. The only thing that has been a problem is a hunting idle problem when using stock type holleys. Jeff from modern knows how to tune them up. I have seen guys go 8.50's with one. My old car has gone 8.80's so they cant be that bad if you are looking for that style. Yes there is some single 4bl manifolds that make more power.