Miata MX5 RoadsterSport Exhausts

Pictures, Videos, and other MX5 Miata RoadsterSport Exhaust Info.

GENERAL BACKGROUND on MX5 Exhausts

MX5 Miata Exhausts for 2006-2013 MX5 Miatas add power and fun! Good-Win Racing makes and sells more exhaust choices for the MX5  Miata than any other company, and we use that experience to help YOU find the best MX5 exhaust choice. We provide an estimate of how much louder each exhaust choice is over stock sound levels in the product description for most of our MX5 Miata exhausts. We have MX5 Miata exhausts designed for street use, race use, as well as MX5 Miata exhausts designed to handle a performance header or MX5 Miata supercharger.

One VERY important factor to consider is how factory options change the listening environment of the MX5 driver. The driver of a manual transmission soft top equipped MX5 Miata has a VERY different vehicle in terms of sound dynamics than does the owner of an automatic transmission equipped folding hardtop MX5 Miata.   The hardtop is an echo chamber in comparison to the soft top Miata.  Thus, street drivers of otherwise stock manual transmission soft top equipped MX5 Miatas tend to prefer louder exhausts choices such as our best selling RoadsterSport II or our Racing Beat dual tipped exhaust. However, owners of automatic equipped MX5 Miatas, and any MX5 owner with a folding hardtop, usually prefer the RoadsterSport Q Dual exhaust. All owners considering further modifications such as our performance headers, performance midpipes, and superchargers, are strongly encouraged to consider the RoadsterSport Q or new RoadsterSport SuperQ.

Finally, we offer BOTH a “Race Single” and “Street Single” that are designed for the sound limits of SCCA events and tracks such as Mazda Raceway Laguna Seca, though some will find them appropriate for their street use. If you have any questions about which MX5 exhaust is best for you, please contact us by email or phone today.

MX5 Race Single:

ROADSTERSPORT STREET SINGLE…Watch entire video for Drive By!

ROADSTERSPORT II DUALS

WHY THE STOCK HEADER is TERRIBLE… Primaries are Pinched Almost in Half.

When you pull the heat shielding off the stock header you find unequal length primaries that are too short and PINCHED IN HALF as they enter the collector!

Once you see the FACTORY HEADER without heat shield you understand immediately why you can’t make much more power without changing the header.  Notice how the stock header primaries are too short, not equal length, pinched in half above the collector.  Therefore, serious MX5 performance starts with replacement of the factory MX Header.

Now let’s look at our RoadsterSport STREET Plug and Play Replacement MX5 Header!

RoadsterSport MX5 STREET Header

Our RoadsterSport STREET Header  is a PLUG AND PLAY replacement for the pinched off stock header and features:
-MUCH Longer, equal length runners
-High-flow 5″ round, 200cpi Ceramic Core Catalytic Converter
-49 state legal cat (EPA and OBD2 compliant, but NOT CARB APPROVED for California, the Carsound 99659HM core is an EPA certified converter covering up-to 6.2L/6375 lbs so it easily handles the flow of our performance header while still delivering clean tailpipe emissions)
-Bolt-in design for MANUAL TRANSMISSION (see our forum header install thread for details of installation on automatic transmission).
-Bolts to RoadsterSport MX5 Midpipe…or stock MX5 midpipe. Also saves weight, factory header assembly is 15.2 pounds and this RoadsterSport MX5 Street Header with converter is just 11 pounds! Converter has two year manufacturing defect warranty (normally aspirated cars only, NOT recommended for supercharged cars), the rest is all stainless steel and has a LIFETIME warranty, even the flanges!

Take a drive and hear the RoadsterSport Street header matched to our RoadsterSport Midpipe and RoadsterSport Q Exhaust (we off this full COMBO on the site).

For those wanting even more we off our RoadsterSport MAX POWER COMBO, consisting of our RoadsterSport Max Power Header, RoadsterSport Midpipe, RoadsterSport Q Muffler:

DYNO WORK—CLICK HERE FOR GRAPH

On a dyno dynamics unit with our 2006 MX5 Miata we were stock 130 to 132 at the wheels across several runs (remember that the factory claim of 170 is “crank” horsepower for 2006 and 166 crank hp for 2007 under the new testing procedures). These results are identical to what AEM and Grassroots MotorSports got for stock on their project cars. With the AEM intake and RoadsterSport II exhaust we hit peaks of 145-148 depending on the run…again on a Dyno Dynamics unit. Figure about half that for the AEM intake (which is in line with their claims and dyno charts) and half the exhaust.

Note that the The Dyno Dynamics dyno is an eddy-current dyno, it is not an inertia dyno. Without getting into that debate about what is a “real dyno”, just understand that when you see stock numbers of 145 to 150 then it is likely it was from an inertia dyno (Magnaflow NC exhaust advertised results for example). Conversion between these types of dynos is rough at best….and it is much preferred to compare apples with apples by doing all before and after tests on the SAME DYNO.

Now to the dynos comparing mods. THREE levels of mods below.

LOWEST line is our best NC dyno run with AEM intake and our RoadsterSport Q, a nice gain of about 14-16 horsepower over stock NC.

MIDDLE run adds the midpipe change. This midpipe change was VERY interesting. Did several runs and they all look like this with a very slight loss of 2 peak horsepower but a gain of 5 to 8 Ft/lbs of torque from 3500 all the way past 6000 rpms.

HIGHEST RUN adds in our RoadsterSport header. NICE 158.9 hp and 137 Ft/Lbs!! This is Header with our midpipe and exhaust and the AEM intake. Note that the RoadsterSport header does NOT have hookups for O2 sensors, but we sell the extension cords to make this install plug and play. The RoadsterSport midpipe includes TWO O2 sensor bungs, one before and after the catalytic converter to make it easy to relocate the sensors with the optional extension cables to avoid codes. Our RoadsterSport Midpipe uses a massive 18 inch long resonator to keep sound the same despite the gain in flow over the stock unit… but adding header will add a lot of sound. If you like old Italian Fiats and Alfas then you will love the sound of this car with the header, and those with more delicate sensibilities should consider our headers that include a converter in the header itself. Note the interesting comparison with the Grassroots MotorSports project NC Spec Miata; we started with the exact same baseline results and finished almost the same, 2 hp and 2 ft/lbs stronger, all the gains of the full race system without the full race system noise.

For MORE on they dyno work, including MANY pages of forum discussion followup, please see the FORUM DISCUSSION.

UPDATES 2012:  Our header options have expanded significantly and in addition to our RoadsterSport and Racing Beat headers we now have our PPE headers, one PPE MX5 Miata Header with converter and one PPE Long Tube header for max torque.  See our forum discussions regarding the Long Tube PPE header and on our project 2012 MX5 for details on our prototype RoadsterSport Street header with converter.

RoadsterSport Muffler INSTALL NOTES!

VERY EASY…directions and discussions in more depth in our FORUM INSTALLATION THREADS (only muffler install summarized below).  Complete Header and MIDPIPE installs also covered in our forum installation section.

Spray WD-40 on the nuts of old exhaust flange nuts (also on the threads that hold in the baffles if you plan to remove those).

Squirt some soapy water in and around the lower portion of the rubber exhaust hangers and you may want to yank the old exhaust back and forth to work that soapy water into the surface between the rubber hangers and the metal hooks that hang it from the car.  Getting the hangers good and lubed up is the key to getting old muffler off easily….and the key to get new muffler properly installed easily….I will liberally put dish soap in the holes of the rubber hangers and on the new muffler hangers before I lift it into place.  Note that I ALWAYS leave the factory rubber hangers on the Miata!   The reason is so that you don’t mix them up, notice they have asymmetric layout from the factory to counter the direction the engine leans on the driveline when you hit the gas.

Remove the nuts on the old exhaust flange using a 14 mm deep socket or whatever fits (if you don’t have a deep socket, you can use a regular socket, however the ratchet won’t seat all the way down on the socket, so you have to hold it straight using two hands). Remove factory ‘ring’ style gasket on the midpipe.

Note: the exhaust midpipe will support itself during the change over

Coax the old muffler off the rubber support bushings using a piece of wood or long screwdriver or pry bar.

Hang the new muffler with LOTS of dish soap on the hangers so it easily slides into the factory rubber hangers.  Adjust it on the hangers until you get the flanges nice and flush (you do not want to ‘jack’ the muffler flanges into position with the hardware). Torque the supplied hardware to 25-30ft/lbs.

You are done….unless you want to pull the baffles. The baffles make the muffler a little more quiet. If you want to pull them, find the bolt that holds them in…which is about 6 inches under each tip. Unscrew that bolt just HALFWAY and use it as a handle to jiggle the baffle loose. Then unscrew the retaining bolt the rest of the way and slide out the baffle.

Note the factory pipe sticking out of the midpipe is smaller than the flange accepting it (we use the same flange on the Q, RSII, Street Single, Race, etc). Thus, take a few minutes to line up the flanges properly (lube up the hangers good!), and it slots together perfect every time.

Had a few calls over the years with folks having issue getting muffler sealed neatly. Too many have read forum myths about using the factory round gasket…which too often leads to customer bending the flange ears and then they need liquid gasket maker to get a seal (solving a problem they didn’t have to create).   The error seems to start hanging the muffler without enough lube on the hangers to allow proper adjustment….and then they use the hardware to JACK the flanges together.  Somehow they are then shocked that the flanges are not flat together and they start playing with factory gasket again.  Note this error will happen with ANY design of flange if you use the hardware to jack the parts together. Had a customer drive all the way from Los Angeles because he was just sure that his would NOT fit together as shown here and on inspection we found dry twisted hangers pulling the thing in several directions at once….and he had jacked the flanges together with the hardware. We unbolted it, lubed the hangers real good and took maybe two minutes to get the flanges together properly….and then it bolted it up perfect. Thus, a little common sense during the install, LOTS of DISH SOAP AS LUBE in the hangers, and a torque wrench (25 -30 ft/lbs), will do it nice and neat every time.

Our RoadsterSport flange swallows the SMALLER factory pipe.

Note flat meeting of flanges between factory midpipe and a RoadsterSport muffler, using our flat gasket between these surfaces is the best way to keep that fit flat and sealed.

Another Before and After Sample

Before starting the install of the new supercharger we wanted to finally test the PPE Long Tube on the same Car, same Dyno as our RoadsterSport Max Power Header. Our results with the RoadsterSport Max Power header were done in August and it was hot and humid (bad conditions for making power). Nonetheless, we had one day last week that was a near perfect match for the August test date, and so we tested the PPE Long Tube with the same 60% humidity and same low barometric pressure and temperature just one degree cooler, conditions as identical as possible to our August test of the RoadsterSport Max Power Header on the same car, same dyno. No other changes besides the header swap. The results of that test last week were so bad for the PPE Long Tube that I did not post them, because it was obvious the car had pulled lots of timing. I even suspected the fuel in the tank had gone slightly stale.

So, I ran down the fuel in the car so we could load 100 octane last night and test again this morning. This morning was just 48% humidity and nearly 10 degrees cooler than the prior tests. Thus, together with a tank of 100 octane we are cheating BIG TIME in favor of the PPE long tube….yet the RoadsterSport Max Power Header still won the contest.

The results are not quite what I expected. Basic header design theory suggests a narrow long tube will sacrifice the top end to provide better torque down low and through the midrange. Thus, I assumed the PPE Long Tube would own the bottom through midrange and not do well on top (RoadsterSport Max Power header primaries are shorter but BIGGER diameter). As you can see from the dyno below, the gains in the low and midrange for the PPE Long Tube are about nothing… and the cost it pays from 4900 and up is too much.

Bottom BLUE line is original best of stock runs
Top RED line is Best RoadsterSport Max Power Header August session
Green line in the middle is PPE Long Tube Today.

RoadsterSport MX5 STREET Header