'99 head HP gains?

I'm intrigued by the idea of the '99 head swap to an NA for people wanting to gain some HP but not wanting to supercharge or turbo their car. It seems like the most reasonable way to increase power out of the typical bolt-ons, considering most people say that the Mazda system is so well engineered and that most aftermarket stuff provides little to no gain (well, at least on the pointy board that's what they say).

I've done some searching, but have found nothing in the way of a before and after dyno test on how much this swap increases horsepower. Has anyone else seen hard numbers? I'd be interested in seeing them.

Regards.

Ask me when I finally get my '99 head installed...

I've heard that there's anywhere from 10 to 20 whp to be gained from the swap.

EDIT: The other added benefit is that you get rid of those pesky hydraulic tappets. No more clicky-clicky...

Tricky, how long are you going to wait?! I found a dyno-day thread from January where you were saying you needed to get that done. The community needs hard numbers! Help us out man!

Do you remember where you heard the 10 to 20 number? That seems like a pretty big spread.

Seems like I remember hearing 7-10 HP gains. Search Miata.Net for other's results. Don't forget that you will need a matching Intake Manifold.

Well, I've had the thing in my garage for a few months now (like, maybe 24), so it's probably time to go ahead and schedule the damn tech day. I really want to get it done before Hallett - and before the weather gets too hot - so I'm going to say it'll happen before the end of June. At this point I might as well do another TB/WP job while we're at it. ;)

I think the numbers I got were from some guy on M.net who had done such a swap, but it was more like third hand info.