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After months of testing and hours of dyno tuning we are proud to introduce one of the best bang for the buck mod for your naturally aspirated NSX. The NSX from the factory comes with 240cc injectors... quite small for the displacement of the NSX. As with most Honda injectors the NSX injectors from the factory run high duty cycles stock and in this case if you do any exhaust modifications such as headers, test pipe/high flow cats and exhaust it will cause leaner conditions. The best way to resolve that issue is to either raise the fuel pressure or install larger injectors and that's where the RDX injector comes in

The RDX injector is a popular mod in the B/H/K community for people looking for a reliable and affordable injectors for their turbo or high hp N/A build. The RDX 410cc injector is a modern injector with an excellent spray pattern which helps with the combustion process. The injector also offers excellent idle characteristics thanks to an increase in control of the injector.

Dropping in larger injectors is only recommended if you have an aftermarket engine management system or our new Prospeed RDX Spec program. Your car will not idle or start if you install larger injectors without adjusting for the size with your engine management. The Prospeed RDX Spec program is custom tailored for the RDX 410cc injector. We have spent hours on the dyno to fine tune it and now we have a perfect alternative to a AEM FIC or AEM EMS. The RDX Spec program idles like the factory injectors and produces some serious hp and torque gains.

It's time to get rid of your 20+ year old injectors and install an easy plug and play "bolt on" mod for your NSX. Next to headers and exhaust nothing comes close in terms of bang for the buck in the performance category for N/A NSX owners.


We offer the complete kit for your 91-94 NSX both automatic and manual NSX's are supported.

Prospeed RDX injectors & RDX Spec Program kit includes:

  • 6 New factory sealed Acura RDX injectors.
  • 6 OBD-1 to RDX injector harnesses and top hats for injectors and bypass plug.
  • 1 PROSPEED RDX SPEC ECU ROM tune service. You will need to send your ecu to us to reprogram your ecu.

We also offer the RDX injectors and install kit for your 95-05 NSX both manual and automatic.

The kit includes an AEM FIC with harness adapter for plug and play operation. You will need to come in for tuning. PM for details.


$425 for injectors and installation kit only. $349 for Prospeed RDX Spec ECU service.


  • If you purchase the Injectors/Installation kit with the RDX Spec ECU service it is only $749 shipped.
  • If you are a previous customer you will get a discount and if you already have an ecu done by us the upgrade is only $100! So you would only need the injectors and installation kit!
  • If you have a 95 to 05 NSX our RDX injectors and installation kit will work for you. You will need a AEM FIC or AEM EMS and you will need to have it tuned for the larger 410cc injectors. We offer both the AEM FIC and AEM EMS... PM me for prices.
  • All NSX's who upgrade to larger injectors will need to have our ECU ROM tune or aftermarket engine management system if not your car will not be able to run.


  • Brand new modern OEM injectors vs your 20 year old injectors.
  • 410cc at approx. 38 psi vs 240cc (Stock) which is enough fuel for a 350hp NSX.
  • Compact light weight components which allows the injector to be responsive and idles nicely for a large injector.
  • Excellent atomization which produces a more efficient combustion= more HP and fuel economy.
  • Runs at a safe duty cycle vs the OEM injectors running close to 100% duty cycle! 80% is industry standard of being close to max.
  • As you modify your NSX (I/H/E) your car will need more fuel and will run lean if you don't supply more fuel. The RDX 410cc is sufficient to handle it.
  • Plug and play and easy to install with the Installation kit.
  • Price... at about $53 retail each you can beat the price.


Heres a link to a Fuel Injector Worksheet. Put in the NSX values of 270hp for 3.0 and 290hp for 3.2, BSFC for NA is .45 or .50, 6 injectors, and .8 Duty Cycle


Here is a video of the RDX injector in action. Video belongs to injectorrehab thanks.

Here is a graph showing the Flow vs. Pressure for the RDX injectors. Image courtesy of INH.


91 NSX 5 SPEED with K&N filter,Comptech Headers,Stock cat and muffler.

Dynapak Dyno

We tested the OEM ecu vs. a Stage 3 rom tune vs. RDX Spec Program and here is the results.

  • The dotted green line is the OEM ecu with stock factory 240cc injectors
  • The fine green line is the Prospeed ROM tune program with stock factory injectors
  • The blue line is the Tuned Prospeed RDX Spec tune with Factory Acura RDX 410cc injectors

We noticed a whopping 37 ft lbs of torque increase at 4200 rpm over stock and over 16 whp on top in VTEC. A combination of a superior injector and a properly tuned ECU really helps the NSX run safer AFR with an ideal idle and part throttle drivability.

Here is the AFR of another 3 dyno runs, the blue run is the the AFR for the Prospeed RDX Spec ROM... Fine tuning allowed us to get to a more ideal 13.0-13.7 AFR. We are happy with the AFR as it is safe and allowed us to run a little more timing.


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