Do as you wish, but bothering with that intake manifold is an abject waste of time and consumables.
Here are the results of an abject waste of time and consumables:
First, the racecar head came back and we had a better way to calibrate the flow bench instead of assuming all the stock ports flowed the same. This revealed that all the prior numbers were fairly optimistic, which I believe because it all seemed a little too easy.
Next we flow tested the B230 and B21 manifolds on a stock port. No restriction noted for either.
What gives? Turns out it'd probably help if you plugged all the ports on the manifold...
After this our stock port and stock B230F manifold threw down these absolutely putrid numbers:
.050" 19.6
.100" 51.7
.150" 80.3
.200" 105.1
.250" 118.4
.300" 126.3
.350" 130.4
.400" 124.7
.450" 124.7
.500" 124.7
.550" 126.3
.600" 127.1
So, not much more flow than the exhaust port. Awesome.
Esmth donated this B230F manifold which got cut up and eventually ported in the name of science:
First thing to note is all the nasty bosses in the plenum area. Those got cut off and the runner entry got smoothed particularly on the short side. Cylinder 1 and cylinder 3 are especially impacted by the throttle body stud bosses, one of which was good for some 8 cfm at peak on its own (I forget which, I think #1)
The injector bosses on the B230F manifold can be slimmed down considerably although this made only a small difference in our tests.
The big ticket seemed to be in widening the runner near the port entry, particularly on the long side.
Fortunately for me my dad took good notes of what the final product ended up being, in the name of repeatability:
And I made this little tool, which you can have the STL file for if you ask nicely (or tell me where I should upload it):
The narrow end goes in the injector boss area once porting is complete, and the wide end goes into the widest part of the runner until the notch is no longer visible. Here it is, not going, plus the first few layers got too squashed:
and of course the final results, before and after:
.050" 20.4 20.8
.100" 50.7 51.2
.150" 79.1 79.7
.200" 103.0 104.4
.250" 120.7 121.5
.300" 134.6 135.5
.350" 144.4 147.1 +1.9% (gainz not worth noting up to this point)
.400" 147.1 154.7 +5.2%
.450" 149.0 160.7 +7.8%
.500" 149.9 163.7 +9.2%
.550" 149.9 157.7 +5.2%
.600" 150.9 157.7 +4.5%