are shumacker headers restrictive?

many thanks for the input! much appreciated, ive been running them for a couple of years with my settup. only went with them as <at time>i was advised they were only header that will allow me to fit 440 into A body without cutting fenderwells, i did try a cast jensen interceptor, the engine as we lowered got "wedged" and we hoisted it back out and all i could do was order and wait for what i thought would work......im now at a point where im thinking ally heads and cam im already running a dual plane ally inlet and holly 750, are these shumackers any good at all ie over originals and if im after more beans should i just change headers and if so to what? cheers again .