ive seen guys take the factory manifold and flip and works good,my question is what tube size header would i need if i have a 370 or 408.1-3/4-1-5/8 need help thanks guys

 

I had the same question. Flipped manifolds make good power, but my project deserved some headers on it from a visual stand point. It was then I leaned on my cam guy (Martin Smallwood) for advice. He fealt i couldn't go wrong with either choice, but at rue level I'm at 1-3/4 primary's would be ideal, but even then the T6 housing is still the restriction