A bit on quench pads here
quench pad?? [Archive] - Tampa Racing
quench pad?? [Archive] - Tampa Racing
X2My head hurts after reading the first page
There is nothing wrong with the C4 head. In fact, if anything the C4 head is the superior B-series head. Flow wise there is nothing between them. The C4 head also has "quench" pads unlike the B16 head which is a bonus.
Im not the Most experienced in flow ability's and characteristic of ports and heads but had a go a while back comparing the 2.
http://www.ek9.org/forum/engine/32598-b16a-b-b18cr-5-6-b18c1-4-gsr-head-differences.html
Wouldn't really concider the P72 Head as bad, it just has different characteristics.