most people that do LS/VTEC swaps usually dont just slap a vtec head on an ls block, most of them pull the block apart and put in higher compression pistons and stronger rods for the higher rpm range, and vtec heads flow better than ls heads and the intake manifolds are different, now on the sohc motor question, i havent a clue if that statement is even true, most people do sohc mini me's to make more power and that is usually how it turns out........