W2 heads on a 318

yellow rose said
Even with a 2.02 valve you will see a power increase by notching the bores. Guys fit 2.02's in there and don't notch the bore, but it should be done.

Otherwise, no reason not to do it.

I never notch anymore except when physical interference mandates. I think the crevice volume kills more power than any flow increase. J.Rob