RuffCat

you'll never win with B heads N/A. Cannot go wrong with a centrifugal that drives normal in the city with better mileage and has more than 300rwtq at 2200rpms when you get right on it. If you were to buy new(as I picked this up used), than I would have to say a KB twinscrew is a must! You would have instant hp and tq and be much more efficient. Eitherway, the old school saying was "there's no replacement for displacement" until.....Power adders came along.

You will have a hard time getting over 400rwhp out of an N/A cobra with B heads that are streetable, but it can be done!
IMHO, going here and there to this show/meet saying your 400rwhp N/A means nothing these days. Saying your 500rwhp blown draws all the attention and doesn't hurt the respect factor whatsoever like most feel that it would. It's by far the easiest way to make power and there are lots of parts out there if you have issues for replacement. Anything much over 500ish rwhp requires a bit of work for supporting mods although you should have them B4 500 anyways.