All the VTEC motors have the oil breather chamber on the back of the block and the PCV valve mounted on the intake manifold. However, on the newer non-vtec motors, Honda deleted that breather box and put the PCV valve on the valve cover. If we are going to put the VTEC Head on the block, we will have to copy that system. What you can do is to drill a hole, tap it, and put a nipple as shown in the pic. Then run an oil catch can, between the PCV valve and the intake manifold.
info taken from (http://honda.hybrids.jp/b20tech/b20-pcv.shtml)

i was just wondering how neccessary this step is and if you have to absolutely do it.