Originally Posted by felixthecat
Yes I agree w/ you. ^^^^^ I'd just throw a 23 on board. Mazda's MX-5 is a 20 w/ 170 hp. I'd bet they are using a 23 head. The head on the 20 foci has smaller ports for velosity= air flow, for the shorter stroke. Its not like a lot of regular joes are driving MX-5's.
Yea the higher horsepower MX5 2.0 motor probably has higher flow heads mated to a more aggressive cam grind. This pushes the powerband upstairs and keeps it broad, instead of killing the bottom end with oversize ports and killing the top end with a wheezing cam profile.
IMO, big heads with stock cam is a total loser....just like a bigger cam mated to putzmobile econobox ports (optimized for low end).