If you’ve ever added a turbo to your Miata, or plan to, you already know that routing a clean, reliable coolant line to your turbo is anything but straightforward. The factory coolant mixing manifold, found on 1.6L and 1.8L engines, wasn’t designed with forced induction in mind. It’s bulky, awkward, and often the cause of poor fitment, clearance issues, or ugly engine bay routing.

That’s where R Theory Motorsports’ Low Profile Mixing Manifold comes in a purpose built, modular replacement designed to solve coolant routing problems on turbocharged Miatas while also delivering a cleaner, simpler look for N/A (naturally aspirated) builds.

The Problem: Messy Coolant Line Routing on Turbo Miatas

Turbocharging a Miata is exciting, until you have to route a coolant line to your turbo. The OEM coolant mixing manifold sits at the front of the engine and only works well with the stock layout. For turbo setups, it often means hacky hose routing, leak-prone adapter fittings, or sending your manifold off to be welded just to get proper turbo coolant flow.

Even if you’re staying N/A, the factory manifold takes up space and crowds the front of the engine bay—making it less pleasant to look at.

The Solution: A Clean, Bolt-On Coolant Routing Upgrade

R Theory’s Low Profile Mixing Manifold is a drop-in replacement for the factory unit, machined from aluminum and anodized for durability. It’s compact, sleek, and far more versatile, making it the ultimate coolant line solution for turbo Miatas and N/A builds alike.

Because it hugs closer to the water pump, the manifold frees up space and gives your engine bay a tidy, professional look. Whether you’re running a custom turbo kit or just trying to make your N/A Miata easier to maintain, this is the part that makes it all simpler.

Modular Fitting Options for Turbo and NA Setups

What sets the Low Profile Mixing Manifold apart is its pre-threaded outlet port, which accepts a range of fittings to match your setup:

• For turbocharged Miatas: Run -4AN or -6AN fittings to cleanly and securely route coolant to your turbo. No more custom welding or janky adapters—just choose your fitting and install it with confidence. For daily-driven builds, the 5/16” hose barb is a great option for simpler routing and easier maintenance.
• For naturally aspirated builds: Select the 5/16" hose barb fitting to retain your factory coolant hoses. You still get the benefit of a cleaner layout, better access to surrounding components, and a more streamlined engine bay.
• For minimalist or custom setups: If you’re deleting your 5/16” coolant lines or pulling coolant from a different location, we offer a plug option for this port—making it ideal for simplified turbo or custom N/A builds.

This level of modularity makes it one of the most versatile Miata cooling solutions available today.

Support for Heater Core or Heater Delete

On the other side of the manifold, you’ll find another pre-threaded port for your Miata’s heater core line. We include an aluminum hose barb and a high-temperature silicone heater hose to replace the stock rubber unit—which often looks out of place in an otherwise well-done bay. For added protection, an optional Thermal Sleeve is available to shield the hose from extreme temps, especially useful for track cars or hot climates.

If you’ve deleted your heater core entirely, we also offer a plug for this port, so you can seal it off cleanly without any extra fuss.

Why Miata Owners Are Upgrading to This Coolant Manifold

Whether you're deep into a turbo build or just refreshing your naturally aspirated Miata, R Theory’s Low Profile Mixing Manifold offers real advantages:

• Cleaner engine bay layout
• More reliable coolant routing to your turbo
• Simple installation with no welding or custom fabrication
• Improved serviceability and access

Combine it with other R Theory cooling system components or run it solo—either way, it’s a noticeable upgrade that delivers both function and form.

Key Features

• Direct bolt-on replacement for OEM Miata coolant mixing manifold (fits 1.6L and 1.8L engines)
• Low-profile design for a cleaner engine bay and better clearance
• CNC-machined aluminum body, available in black or blue anodized finishes
• Modular outlet options: -4AN, -6AN, 5/16” hose barb, or plug
• Compatible with turbo and naturally aspirated Miatas
• Includes upgraded heater core hose and optional Thermal Sleeve
• Compatible with factory power steering
• Not compatible with A/C systems

Looking for a Better Coolant Line Solution for Your Miata Turbo Setup?

This is the upgrade that solves your Miata turbo coolant routing headaches while also giving your bay a tidy, professional finish. Clean, simple, functional.

Check out the Low Profile Mixing Manifold and make your cooling system something you don’t have to think twice about.