Hey all,


I’m currently in the planning stages for a turbo setup on my 1.8 NA Miata and looking for advice on modern, reliable manifold options that can handle 300–500whp. I’m aware of some of the older tried-and-true designs (Bell Engineering, Flyin’ Miata, etc.), but I’m interested in hearing about what’s available now especially anything with updated designs, materials, or manufacturing methods.



A couple of questions:

• Are ISR manifolds still a solid choice in 2025, or have they fallen behind in quality/performance compared to newer brands?
• Any notable smaller fabricators or boutique brands worth checking out?
• For the 300–500whp range, is a cast manifold still preferable for durability, or are modern tubular manifolds holding up just as well?

Build goals:

• Street/track mixed use
• 300–500whp target
• Good spool characteristics (not just peak power)
• Reliability over chasing every last hp

Would appreciate any firsthand experiences, dyno results.



Thanks in advance!

 

What's an ISR manifold?

Kragen's manifolds look great.

 

Kraken or Flyin' Miata cast manifolds. Both have proven reliability on the street. Kraken is a little more heat resistant on the track. Some will say Flyin' Miata is less reliable on the track, but I know some who have used them and never had issues.

 

Kraken all day long. Its cast, but with shaped runners and flows excellent. The new FM is also similarly designed but more pricey. Worth it if you are looking for a kit, but for a DIYer kraken is proven and cost effective.

 

I have been running a Kraken manifold on my race car since 2018 and have never had a single issue with it and would highly recommend. I will probably be selling most of my turbo setup soon also if you are interested...