Ask Emelio and Shanker how they did it. Both are 168+ depending on weather. On stock VVT long blocks.

 

I suspect neither is willing to share

 

They talk numbers. But I've yet to see a dyno sheet or discussion of "work" performed.
I do know they have EUDM intakes, and Shanker has a parts bin balanced bottom end. Along with a proper valve job and port matching.

 

I assume the car you're talking about is the rental. There was a thread about it on m.net a while back. It's got a 01+ bottom end, but it's not a vvt motor. It's running a 99-00 bp4w head.That head isn't stock either. It's shaved, and has some valve bowl work at the minimum. It's not running a stock cam either, it's running a BP5A mazdaspeed cam. Not to mention it's running AEM engine management. It's an impressive little car, but you're not going to make 170 n/a whp on any miata motor without opening it up.
949 Racing Rental Page
Dylan

 

Big difference between opening an engine and rebuilding it with "stock" parts. And rebuilding it with Carrillio rods, high comp pistons, big cams, etc....

 

Costs for labor are the same, unless you do the work yourself. I wouldn't call that headwork stock either. Really beside the point though. I was really speaking more to y8s when he said:
Dylan

 

The head work required to make the flow needed passes tech for several stock based classes.

Now, if you want to take a crate motor, bolt some crap on to it and tune it. No, 170 isn't gonna happen. If you have a high mileage motor and want to do a proper build, yes 170+ is possible.

 

If you think shaving .020 off the head (which should bump compression by about half a point, and give that motor around 10.5:1) and valve bowl work stock, I won't argue with you.
Also, I never said 170hp wasn't possible. All I said was that is wasn't possible without opening the motor. Relax.
Dylan

 

Oh, I'm relaxed.
All that work is necessary on a proper NA build. But you can still make those numbers using essentially stock parts.

 

ok i revise: open up my bottom end

honestly I dont think there's HUGE gains to be had from bumping compression via the pistons but maybe from balancing and lightening the rotating assembly. headwork is a must in any case.