JohnnyTightlips Build "Maximum Carnage"

Exhaust is just as important as intake. If you can get more air in but can't get the increased volume out then you're actually hurting performance.

Every single head minus a billet/CNC head made from scratch is different than it's counterpart. There are so many variations in casting and molds that even though they look the same there are differences in millimeters.

Getting an almost mirror finish on the exhaust side will help since carbon/soot would be less likely to accumulate. On the intake side for MZR engines you could go a little smoother but you still want some turbulence to keep the airflow rate up. Too smooth and it actually causes air to stall/slow down.

Gasket matching does work and helps but you gotta do both sides. The manifold and the head. If you have a hard edge then the air will hit it and dampen the porting affect.

I also forgot to mention that on the Speed heads they have a split port design. Now porting the intake to make one large single runner is ok however I would refrain from doing that to the head. Keep the division in the cylinder head. Just knife edge it. You'd split the incoming flow sooner but keep the velocity of the intake charge and have the increased volume.

There's an article out there where a performance shop tested porting a head with split port design and by removing the divider in the head they actually lost cfm but when they kept it and knife edged it they gained cfm.