BP5A-12-420 cam specs

This is the stock intake cam from the 04-05 Mazdaspeed or "MSM" and also the 99-00 JDM BP4W heads. The JDM N/A car uses the same cam gear as the USDM N/A. The MSM gets a unique cam gear.

.346 total lift
257° @ .010
I didn't extract the lift at .003" yet.

I'm not an expert on this but it looks like the duration at low lift is close to the OE intake but expands to the same duration @ .300" lift to match the OE exhaust. That means a squarer nose and slightly higher valve acceleration than any other USDM Miata cam that I found. I wonder if that's why the MSM has a lower redline and if the higher redline JDM BP4W had stiffer valves springs.

So to my untrained eye at least, it looks like the exhintake is still a slightly better option but only by a tiny margin. Much easier to just drop the BP5A in with the stock gear and be done with it.