Re: exhaust manifold porting?
I slightly enlarged the port, and basically smoothed out the bumps on either side. I'd concentrate on smoothing and blending - that's where you'll see the most gains.
I can't comment on how just the manifolds helped, but going from stock manifolds and a single 2 1/4in exhaust to ported manifolds and a dual 2 1/4in exhuast, it was one helluva difference.
1962 Buick Invicta, 407 Nailhead,
Nitrous, ST400 - Manual VB,
V6 ST300 Converter, 3.23 Posi
Viking Performance Suspension,
Front DA C/O Kit, Rear DA Shocks