About the springs:
FM springs are well known for providing a good balance of street ability and track performance. Their combination of ride height - giving the suspension room to work - and spring rate means your Miata will ride and handle better than you would expect from a set of performance springs.
There's more going on than you think, though. See that section with the tighter coils? Those are designed to act as a secondary spring, keeping the spring from going loose under full droop. While these rates might sound high compared to some other springs on the market, they are stiff enough to keep your car off the bumpstops. Softer springs will often give a worse ride because they allow you to blow through your suspension travel and end up on the stops. We've specified a powdercoat with a high zinc content for extra corrosion resistance, too.
How much will they lower your car? We can't tell you, because Mazda changed the ride height of Miatas over the years. However, if you measure from the center of the wheel to the fender lip, you can compare your car to the final result. It's not a huge drop but once you drive the car you'll appreciate how well it works.
Specifications for the NC
Front springs: 300 lb/in
Rear springs: 196 lb/in
Front ride height: 13.5"
Rear ride height: 13"
About the shocks:
The Koni Sport shocks have valving that works well with FM springs. They're adjustable for rebound so you can crank them up when you're feeling frisky on the autocross course. They come with a lifetime warranty.
About the sway bars:
Sway bars are used to make your car corner flatter and react faster by keeping the body (and all the weight) under control. Ours are set up for neutral handling and are adjustable so you can tailor the handling of your Miata to your own driving style. Our swaybars are hot formed from 4140 CrMo spring steel. This means they're stronger than the cold-formed bars found elsewhere. We've designed them to keep the same handling balance as your stock sways, but they have two settings in the front and three in the rear for fine-tuning. Includes brackets and urethane bushings with waterproof grease. The NC are hollow front and rear, with sizes of 1" front and 0.75" rear. These sizes are typically not harsh enough to cause damage to the stock swaybar mounting points.