what year is your miata? 1.8 or 1.6? B/c ther is a Exhaust cam mod u can do with the 1.8. By installing the exh cam in place fo your intakecam has proven to have some gain. But you will have to get the extension for the distributor shaved off, or sawed off. But it is proven to get u atleast 7-15hp. Imnot sure if it works with the B6 as well. But with the BP is a cheap mod to do. I just sold one of the ones i had. But i have one more i have yet to install.