why still no plastic intake manifolds from aftermarket companies.

i see plenty of oem ones for some years now.

 

Probably because the casting molds (tools) needed are extremely expensive (more so than when casting alloy). So that you would have to sell extremely high quantities to start making a profit.

The casting mold to make one LEGO brick costs over 100.000 USD. Check out the national geographic documentry on the LEGO (toy) factory if you want to see how a plastic toy is made.

 

yep, edm is correct. tooling is really high for plastic IM. there isn't enough volume for aftermarket Honda anymore. if it was 10 years ago then yes, but it's a bit late now. the actual material cost per manifold would be cheaper than alloys but one will not likely sell enough plastic IM to amortize the high tooling cost.