I have been hoping that someone would come up with a proper intake manifold for an overboosted BP engine.
Begi got one but its $600 and it got very short runners and a pretty small plenum.

I saw a thread over at mt.net the other day which had some good info on the non-US-market 2001-2005 MX5 Sport/RS intake manifold:

http://www.miataturbo.net/forum/t42779/

I especially like Emilio@949Racing post:

Quote
I'll save you guys all the trouble: You want one.

In short, the rest-of-the-worldDM 1.8 manifold is better than the USDM in every way you can quantify. At least 9 small changes add up to a better design overall. I've been trying to set up a supply chain for a few months. Getting closer to that but for now, you're on your own trying to find one. You see, they don't break and dismantlers don't always want to sell long blocks without them. So finding orphans is proving quite difficult. Good luck.

Here is a comparison pic of the 99 vs. the 2001 sport on-us manifold:





One of the reason that it's supposedly better is no VICS or VTCS. The lack of actuators and butterfly make the intake tract bigger and less steep without the bulge after the TB you see in the 99 and VICS manifolds.
Also the plenum and runner volume should be bigger which is a good thing for boosting.

I found one in the UK for £75 that I'll have on my garage floor next week. I'll post better pics then and I'll measure volume by filling it with water and stuff.