Thinking of exhaust mod

I haven't had an H-pipe in 20 years, but from what I remember reading in the hot rods mags, isn't the crossover pipe supposed to be smaller than the exhaust, like 3/4 the size?

Oh, and I'd find another muffler shop. IMHO, any muffler guy who hasn't heard of a crossover pipe wouldn't TOUCH my exhaust system.