If you're looking to upgrade your Mazda Miata from 2006 to 2015, the ACT ZM4-HDSS Heavy Duty/Performance Street Sprung Kit is worth a good look. This isn’t just any clutch kit; it's a solid piece of engineering that combines a heavy-duty pressure plate with a street disc that's been proven to perform. Trust me, once you feel the difference, you won’t want to go back.

The pressure plate in this kit uses a unique diaphragm design that boosts clamp load without the excessive deflection you might find in cheaper options. What does that mean for you? Better clutch life and a more reliable performance, especially when you’re pushing your Miata to its limits. Each diaphragm goes through a rigorous four-stage heat-treating process, so you know you’re getting durability that can handle some serious heat.

Now, let’s talk about the performance street disc. It’s crafted from premium organic materials with a high copper content, which helps with heat transfer. Plus, the steel-backed lining gives it extra burst strength. With reduced marcel, you’ll notice quicker shifts, making your driving experience that much more enjoyable. It’s all about that smooth, positive engagement, whether you’re cruising around town or hitting the track.

Here are some features that stand out:

• Light to moderate pedal effort, so you won’t feel like you’re wrestling with it.
• Longer friction life thanks to ACT’s exclusive diaphragm design.
• Carefully engineered and balanced, using premium organic friction materials to handle heat and reduce fade.
• Perfect for both street driving and racing—this kit doesn’t shy away from a challenge.
• Every component is clamp load tested and dynamically balanced for reliability at high RPMs.

Specifications you should know:

• Clutch Disc Diameter: 8.8 inches (224 mm)
• Input Spline Quantity: 23
• Input Shaft Diameter: 1 inch
• Torque Capacity: 281 ft/lbs, which is a nice bump over OE specs.
• Product Weight: 13.4 lbs—light enough to keep things nimble.

This kit is designed specifically for 6-speed applications, and yes, it comes with pressure plate bolts (M8-1.25 x 20mm) included, so you won’t have to hunt for them. Just keep in mind that the clutch master cylinder and slave cylinder aren’t included, but you’ll get grease and an alignment tool, which is a nice touch.

In short, if you want a clutch that’s built to last and can handle both daily driving and spirited weekend runs, the ACT ZM4-HDSS kit is a solid choice. Your Miata will thank you.