Well I may be ditching the shaved and polished manifold for this NAPS Computer System manifold I just acquired. From what I can gather NAPS stands for Nissan Anti Pollution System and used it on Japanese Market only model L20 & L28 motored sedans like the Gloria & Cedric. The cool part about this set-up is the twin barrel throttle body. At 1/4 throttle the smaller primary fully opens up, after that the larger secondary will begin to open. The advantages will be improved low end torque, better gas mileage, and who knows what else. I don't think if there will really be any disadvantages to this set-up. It's also just really cool! I've never seen one, I think it would look awesome powder coated black with the lettering remaining silver to match the valve cover. Decisions decisions..
NAPS vs N42
Here's a couple links for reference:
http://forums.hybridz.org/topic/32764-naps-l28-intake-manifold-with-twin-butterfly-tb/
http://en.wikipedia.org/wiki/Nissan_NAPS
Regarding twin barrel TB's
http://forums.hybridz.org/topic/39280-p65-efi-intake-manifold/