RoadsterSport SuperStreet for MX5-ND
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RoadsterSport SuperStreet


Stainless Steel PREMIUM ADJUSTABLE MX5 Miata Exhaust

Helmholtz Chamber Design Means Max Fun.

Just 14 pounds!

Gains 8hp in independent magazine tests!

PART NUMBER: 61-1787


Reg. Price: $688.85

Sale Price: $599.00



Free shipping offers apply only to destinations within US Lower 48.

Reg. Price: $688.85

Sale Price: $599.00



Free shipping offers apply only to destinations within US Lower 48.


WHY: Because YOU want to have fun!
HOW: Helmholtz Technology in a Miata Muffler for the First Time!
WHAT: A 2016+ Miata Muffler that you can control, aggressive throaty burble fun when you want with wide open throttle, and super mild when you want to just cruise.

This is a modified version of our all helmholtz Race muffler that adds an ultra efficient high density resonator before the tip to lower the volume while keeping the fun burble and playful character of our Race muffler. We also dress it up with a unique ultra light version of our 3.5 inch RoadsterSport rolled tip pictured below to finish the look for our street customers wanting something more luxuriously finished than the aggressively lightweight Race muffler:

Result is a 14 pound wonder of a street muffler, you get the great look of the RoadsterSport 3.5 rolled tip, the clean flow of 2.5 inches of pipe from start to finish with smooth mandrel bends on the shortest possible path from the midpipe to the exhaust cutout to max your horsepower gains...and minimal weight with these features. How much POWER? Grassroots MotorSports Magazine backed up our dyno results in the December 2016 issue, they tested and found peak gains of 8hp with no other mods, excerpt of that article below:

CLICK HERE to see the full article covering our SuperStreet muffler.

This muffler gives your right foot lots of control over the volume. The effect of the Helmholtz is very frequency specific such that under decel it can get mild and quiet, yet when you push hard toward redline it sounds exotic and racy. With the top down lots of fun throaty burble, but dramatically more tame when the top is up. In brief, FUN when you want it, and mild when just cruising.

How did we do it? We outfitted our 2016 with a computer and sound analyzer and microphones and drove it under varying conditions and loads with and without muffler. We then use that data and some special software to calculate the particulars of the Helmholtz chamber to precisely knock down the frequencies we do not want to hear in the car while allowing the good throaty burble fun sounds to pass through. All this in a muffler that is just 14 pounds, a nice savings over the 21 pound factory muffler.

Ride Along with our RoadsterSport Super Street in a Launch Edition owned by local customer Mark Booth below, big thanks to Mark for the great video!

SHIPPING NOTE...ships factory direct to you. All POLISHED stainless steel construction. Uses stock hangers and connects to either our RoadsterSport midpipe or the stock midpipe.

Proudly made in the USA, emissions legal in CA and every other State of the Union.

IF you have more than 20,000 miles add a fresh donut gasket, our item 61-2144 (factory part number RFK2-40-581). The factory designed the joint between muffler and midpipe as BOTH a flex joint and a sealing point and the impregnated graphite 'donut' gasket slowly grinds itself thinner and thinner. Those under 20k miles usually find the original still works great, those over about 20k miles usually best to start with fresh donut.

The SOUND level is Adjustable by YOU, INCLUDES removable cone baffle insert in the tip that helps YOU select final sound level, baffle in for reduced sound level, and baffle out for more sound...and just one bolt under the tip to make the easy change. Sold separate is an optional packed baffle that cuts the sound a little more if you want...but most won't!

Proudly made in the USA...with a LIFETIME WARRANY!

BRIAN'S APPLICATION NOTES: Famous Miata Racer Andy Hollis recently did his own dyno tests of this muffler and found it flowed as well as no muffler at all, with solid HP gains over the stock muffler, and he added: "BTW LOVE the sound!" Andy's dyno sheet reprinted on page 24 of our forum ND development thread and bottom of this page. Our Race and SuperStreet Twin Tip share the same straight pipe design with result they will make the same horsepower gains, but this is the customer top choice on sound when used without baffles. The little resonator just slightly civilizes the rowdy RoadsterSport Race, it's still very aggressive, with just a bit less high frequency notes in the balance than the pure Race.

Mild when cruising on otherwise stock ND, delivering a classic sports car BARK and THROATY RUMBLE when you wind it out to redline, lots of fun burble when just playing with the throttle around town. Result is TONS of fun, will make many of you laugh out loud. You also get the best performance from the straightest and cleanest flow out the exhaust cutout you can get, and much lower weight. Nonetheless, this choice is NOT for the faint of heart!!! The most common question we will get on this one is: "will it be too loud" and we cannot answer that one for you because the "right" sound level is a matter of entirely subjective personal preference. Our experience is that owners of Automatic transmissions prefer any of our SuperQ choices. This is an aggressive sounding muffler for those who like to go for the redline often!

Not designed for use on car with aftermarket header or aftermarket midpipe, designed for max fun on otherwise stock exhaust system. Adding header adds a massive amount of sound, thus we suggest customers considering adding a header should look to our SuperQ choices for best control of results with header change. The issue with using adjustable length midpipe with this ultra light three hanger design is that customers rarely get the adjustable length set correct and that can put too much stress on the connection between helmholtz chamber and straight pipe. So if you insist on adding midpipe with this design be careful to get length of midpipe accurate (hangers aligned nicely straight up and down for midpipe) and use thicker hanger from the rear to better support the bigger midpipe.


Installation of this Miata exhaust is SUPER EASY...just two 14mm bolts to loosen! When you open the big box you will find separate foam wrap on the exhaust tip, leave that foam around the tip during your install to protect the polished tips and your car's soft plastic in the exhaust cutout. Use gloves. Note the 'bolts' from the factory are actually studs with springs and nuts and the factory usually jams the nuts on so hard that unbolting it will bring the stud out too. If that does not happen then use 13mm long socket to unscrew the studs (or use jam nut technique where both nuts are put on one stud against each other and then wrench used on the inner of the two to back out the stud). Then lube up the stock exhaust hangers with dish soap and yank stock muffler back and forth to work the soap into the rubber hangers and then the muffler will slide off those rubber hangers easily. Then hang the new muffler on the wet and soapy rubber hangers and torque 'bolts' with the springs back in place to 30ft/lbs. Now you can remove foam tip wrap. Option to remove the baffle too, to do so loosen bolt that holds it from under the exhaust tip and use it as handle to shake the baffle loose and then unscrew bolt the rest of the way and pull the baffle (pulling baffle raises the sound slightly). IF not removing baffle, check torque, 15 ft/lbs on the retaining nut will be enough thanks to lock washer included. Note the muffler to midpipe joint is a ball socket connection for the first time on a Miata, it is designed to move a lot, so please do not add sealants that will gum up that dry ball socket joint. Our pipe size is bigger than OEM for best performance/flow, that means the stock donut gasket sinks a bit deeper than with factory muffler 'mouth'. Our flange is designed as a dual purpose item that allows going to flat gasket if you later go with our 2.5 inch midpipe, at which point the midpipe has a flex joint to replace function of the donut and you get a clean 2.5 inches of flow all the way, which is not possible if we stay same small pipe of stock muffler. After install hold you hands about 2 inches from gasket connection with car running to check if you feel 'puff puff puff' indication of leak against your hands, if you do check your install or replace the factory gasket (our item 61-2144, factory part number RFK2-40-581 )



Super Street leaving the line at SCCA Autocross event.

Easily UNDER our local SCCA sound limits on otherwise stock Miata (our SCCA limit here is 93 db at 50 feet and even in the rain our testing found it easily under our strictly enforced sound limits). Also easily under the most strict 92db days at Mazda Raceway Laguna Seca when used on otherwise stock ND.

Dyno Results! From Grassroots MotorSports Magazine's testing, 8 hp from just a muffler on ND1...when the muffler is a straight pipe design like RoadsterSport Race and SuperStreet Single Tip and SuperStreet Twin Tip.

Picture below of Konig Dekagram 16x8 4X100 ET35 Bronze with 205/50R16 tires, lowered on our MeisterR Zeta CRD coilovers, and also showing our RoadsterSport SuperStreet Muffler. Picture Courtesy Customer Brett Riese.


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Customer Reviews

RoadsterSport SuperStreet

Absolutely perfect. I wanted to change the exhaust note without being an obnoxious boy racer and this was exactly what I wanted. Looks great too.

We know inline 4 bangers don't typically have the best exhaust sound, but we love our Miatas and this is a relatively cheap, great looking, light and decent sounding exhaust. Installed it in my driveway in an hour. Tried removing the baffle, and, YMMV but it was waaaay too loud for me that way so put it back and love it. Buy it! You'll love it too.

I will second all of the reviews here and add one more thing. This exhaust has helped me learn proper heel and toe shifting. It gives such a great sound and it's easy to sense exactly where the throttle needs to be or how much to blip. The sound is just glorious, it's fun just to chill thru town now. Love it!

Shipping was fast (Canada). Just received an invoice from Fedex for the duties but I am used to it.
Product came well packaged and in good condition. Was easy to install. Would highly recommend.

Simple to install took maybe 10 minutes sounds great in garage road test in June when snows gone .

So much better than OEM. Very well made and looks great. Nice design and much improved sound. I echo all the previous reviews.

Pretty straight forward installation with several good, instructional videos on YouTube. Soap up the hangers, let them sit for a few minutes, and you are golden.

I drive with the removable baffle "out" and it sounds just like the car should. Nothing obnoxious, no drone, and brings a smile to my face every time.

Once you hear it, you'll know these guys know what they are doing. Great job, GWR!!

Love the sound this produces. I took out the baffle and it's perfect (not too loud during idle either).

It produces just the right tone when the top is down, super fun!

Well what can you say that is nothing more than music to your ears, once you get rid of the tin can oem thing.
It's super easy installation for one person, didn't even lift the car.
It's a balance between good and evil that I can not even explain.
The butt dyno will know the difference in the high RPM range, car just breezes to 7500 RPM now!!
If you don't get a smile like some of the others have posted, then I don't know what will!!!!

Sounds great, maybe even a little subdued. Installation was ridiculously easy. Took about a half hour without lifting the car off the driveway. Fit and finish are perfect, single tip looks just right.

Love it! Except for uttering a few four letter words getting the studs out of the stock muffler, installation was super easy. If this thing doesn't put a smile on your face, you have no soul!

Any discerning customer or more precisely MX5 enthusiast has done their due diligence when it comes to how we are "heard" on the road, right? Starting with a phone call to Good-win racing I can tell you they were spot on and incredibly helpful to help me single out the exhaust making my purchase a one-stop shop--hole in one!

Of course exhaust systems are a very subjective experience. Youtube was very helpful comparing the many options Goodwin has to offer and also other major brands, however, the phone call to Good-win proved how much understanding and commitment this company has devoted to the MX5.

I went with the single tip super-street and could not be happier, and most importantly this product is "wife-approved"--I did purchase the extra glass baffle for the future as an backup plan in case the wife felt this system was to obnoxious--BUT I never installed it!!

I will say: the engine noises went from the front of the car and it is now more honed out back behind the car. The overall tone out the back of my RF and is so pleasant, poppy-burbly (especially when decelerating from 3k rpm). It sounds like an exotic sports well-tuned machine! Definitely not an annoying "rice-burner" sound. It certainly brings a level of safety too-- in my opinion--a bit louder than the stock and yet enough sounds to bring extra attention since it is a smaller/lighter vehicle.

If you did your research-an independent test claims 8hp gains at higher rpms--I will attest that the car is a bit punchier and has benefited with a little more power and I have not noticed any changes in mpg.

This exhaust WILL bring smiles to your face on top of what Mazda has already provided us with the ND2. Thank you Goodwin Racing!


The stock exhaust was too quiet. I daily my Miata and needed a better sound that would not drone on the highway. I installed this exhaust hoping to add a better sound to my car. This exhaust is was the perfect choice for me. I installed it without the baffle and could not be happier. Highly recommend this exhaust.

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