If you're looking for a bit of additional hood clearance when installing a K24 in your 1990-2005 Mazda Miata (NA NB), here's an easy solution. Although we do offer our K24 modified valve covers, we've found that depending on the exact chassis, sometimes the valve cover alone doesn't quite provide enough clearance. 

Because of this, we now offer 1/4" steel laser cut subframe spacers. The front spacers are slotted to allow easy installation without actually removing the subframe from the vehicle. In order to retain the same suspension geometry, you must be running coilovers with adjustable ride height. Just install these spacers above your subframe and then raise your front ride height 1/4" to compensate.