I would agree, especially if it proves to work as good, or better, than the OEM damper.

 

I'd say they operate properly within a spec'd operating range, not "tuned". My guess is some kind of expansion chamber bottoms out above that range.

 

I'm still new to the whole Miata world, But FWIW over in the Evo X world we were facing some fuel pressure abnormalities a little while ago with after market fuel rails and AFPR's, which was exacerbated with larger injectors. around 2000-2200 RPMS, we would dangerously lean out with no real explanation despite having pleanty of pump to support high HP numbers (some guys were running twin 450 pumps and still having the issue). Turns out our OEM FPR's had dampers in them internally and when switching to AFPR's we were unintentionally removing them causing a weird resonance in the fuel rail that couldn't be tuned around. Some guys experimented with the Radium FPD and found it solved all tuning issues related to that 2000-2200 lean spot. The X platform is obviously highly different, as is the fuel system in that it uses a more tradition performance oriented Pump->Rail->FPR->Return setup, but we did have great success with the Radium FPD. We also found a solution to running big pumps at idle/no boost cruising but would still provide full power to the pumps when getting into boost, basically for the same reasons as stated earlier, over whelming the FPR for those running very large pumps (wally 450's in single and twin configurations, twin 320's, etc). It might be worth the little extra expense to swap your regulator to the return side and do the required plumbing, it might make tuning easier as well.

 

Radium Engineering has added a fuel rail that can use their proprietary products including the better fuel pulse dampers to help smooth fuel delivery.

 

For what it is worth, I use the FPD-XR matched to manifold pressure with my FM BFFK at 60psi (matched to manifold) with the damper up at the end of the line right before the T for the two rail inlets. I haven't had any issues though I haven't been logging my fuel pressure. Interesting that there's a fuel rail available now though.

 

Here is a direct link to the fuel rail: Fuel Rail, Mazda MX-5
Looks like a nice piece and price is pretty reasonable at 140 dollars.
Unfortunately if I add the 4 ORB-8 fittings, import tax and shipping it ends up at 300 dollars at my doorstep, but that is still below the price of the Flyin' Miata one.

One thing I do not get: why is the thing not compatible with the '99-'00 USDM VICS manifold? As far as I know the VICS manifold is identical across all markets between '99-'00. We did not get the flattop either until '01.
I guess Radium does not know the rest of the world also had the VICS between '99-'00 or am I missing something here?

 

My guess would be that they designed the rail for a specific car that had a specific manifold on it and didn't really think about other manifolds until too late. The 99 ViCS manifold has the least clearance of any of the NB manifolds, I think.

For those who might be reading this thread and wondering about the results, I did install the Radium damper and it did work. Results got posted in my build thread, but not cross-posted here. Link:

https://www.miataturbo.net/build-thr...5/#post1250082

--Ian