RoadsterSport 4 Helmholtz Polished Stainless Steel Miata Exhaust Muffler for Miata 1999-2005
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RoadsterSport 4 Helmholtz Polished Stainless Steel Miata Exhaust Muffler


The only NO DRONE Helmholtz Chamber NB Miata Muffler.



Reg. Price: $746.88

Sale Price: $649.46



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

Reg. Price: $746.88

Sale Price: $649.46



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


FOURTH GENERATION UPDATE....The Helmholtz chamber revolution in exhaust technology finally available for all Miatas! Our new HELMHOLTZ exhaust system features an exclusive Helmholtz main chamber that massively reduces the standing wave 'boominess' or drone inside the exhaust system! Cuts the 'booming' frequencies of 120-130hz by over 35+db inside a top up Miata cabin which is a common source of complaints with aftermarket exhausts on the Miata. Result is all the FUN throaty sounds you want, without the drone other systems make that wears you out on long uphill and downhill sections of road.

Updated version of our favorite NB Muffler, now the ONLY choice on the market with Helmholtz chamber...AND adjustable sound level! YES, fits manual and automatic transmission. Built in solid 304 stainless steel and completely polished to a mirror finish, this high quality Miata exhaust is our only choice that incorporates a baffle insert that gives YOU some control over the final sound level (baffle in is about 40% more sound than stock, baffle out is 50% more sound than stock... so you always have a choice for those longer trips). Weight is lighter than factory, 18.25 pounds.

For those that want even more sound add our highflow Miata midpipe for more flow and another 10% more sound.

This latest version of our best selling Miata exhaust has both baffle included and a double walled tip for years of lasting good looks while giving you control over the final sound level. And, you always have the option of our packed baffles which are sold here separately.

Install is awfully simple. Disconnect the two nuts/bolts connecting muffler to midpipe. Use dish soap on old stock muffler rubber hangers to get them to slide off. Ideally have exhaust hanger removal wrench handy to make getting the rubber hangers off even easier (even Home Depot now sells them for about 20 bucks). Reverse those steps to install the new muffler. Tighten nuts to 30 ft/lbs

BRIAN'S APPLICATION NOTES: This is an AGGRESSIVE exhaust at full throttle! The helmholtz addition does not make it quiet, quite the opposite, it allows almost a straight pipe full flow design with good control over drone when just cruising so we can let all the fun sounds out at full throttle. The Helmholtz chamber knocks down what most of us perceive as drone by over 35 db but it lets all the rest of the upper frequency fun and pops and burbles right on through! That means by definition this muffler is aggressive, has a ton of attitude on an otherwise stock Miata, and is NOT for everyone! Given that this muffler is aggressive on otherwise stock Miata, it will be really loud, race track loud, if you add header and highflow cat. Designed for the three pedal owners out there who love to zing these amazing sportscars to redline daily. Know who YOU are, if you are actually driving the car around at very low rpms our experience is that you will prefer the mildest bigger mufflers such as our Racing Beat, and in our experience this includes all owners of the optional automatic transmission, and any other owners who drive around at low rpms most of the time. If you hit the redline at least three times on the way to work in your Miata, this might be your exhaust. If you never hit the redline because you are afraid you will 'hurt' the car, please look at our Racing Beat exhausts

LIFETIME WARRANTY, this Miata muffler is made with pride in the USA. YES, includes gasket and hardware needed for install.



Customer Reviews

RoadsterSport 4 Helmholtz Polished Stainless Steel Miata Exhaust Muffler

I purchased the full header back mid pipe and roadster 4 muffler. System is very well built and install was a breeze. Unfortunately unlike the reviews I read that said it was a nice low mellow tone, this exhaust is extremely loud. It is not terrible in the lower RPM range but anything above 4k it sounds like a teenagers straight piped Honda hitting vtec. I spent more money thinking I would get a better sounding and performing exhaust but I do not even want to drive the car anymore.

Installation was simple and came with all the needed hardware. Aggressive sound on demand and little to no drone on highway. I can enjoy conversations in the car, listen to my music and hear things around me with no issues. Glad I bought this exhaust

After months of research and listening to sound clips I was debating on two different mufflers. I originally placed an order for another brand exhaust about 1 year ago. Well after an entire year of backorder and growing tired of waiting I decided to just pull the trigger and get this. I really didn't want anything obnoxious or ricey sounding but I was questioning spending so much on a muffler. Well as hard as it is to make a 4 cylinder sound throaty, this muffler does it really well. I'm genuinely glad I didn't get the other exhaust and I got this. The tone is perfect and not very loud. With the top down it sounds absolutely amazing. It's got pops, crackles, and burbles when driven right. On the highway, there's no drone but it's still slightly audible. City driving was also significantly improved by this exhaust. Maybe you are in the same shoes I was in, looking at the price and wondering if you really want to spend that on a muffler. Trust me, you do. I absolutely love this purchase and I would recommend this for anybody. It's well built and sounds great. Plus, Goodwin's shipping time and service is awesome, unlike some of the competitors. So just go ahead and click add to cart, and I promise you won't regret it.

I had the version 3 of this muffler and loved it. Motor mods (that affect sound) include headers, hi-flow cat, RS mid-pipe and RB intake with K&N filter. It was already reasonably loud but aggressive. Only complaint was the "drone" noted by many in the 2-3k RPM range, especially on highway. Not really "bad" but definitely noticeable. I watched the video for the RS 4 and decided to go ahead and treat myself to the upgrade, though not really expecting anything earth-shattering and wondering if it would really be a big enough difference to justify the cost. (after all, I already loved the ver. 3). DAMN. It was worth every penny. It completely changed the exhaust character of the car. It is actually quieter and more enjoyable when driving around town at partial throttle and low/mid RPMS. HOWEVER... be warned, the minute you cross 3,500 RPM "the monster awakes" and it sounds great. At FULL THROTTLE it is REALLY loud. Just like Brian says, "race track loud." You will want to be very careful if you like your neighbors. But when you put your foot to the floor it is just glorious. At every stoplight, I can't help but hear Will Buxton saying, "And it's lights out" when the red light switches off and I run through the gears with the pedal on the floorboard and the engine screaming." (after checking for cross traffic, of course) It really has changed the character of the car. BUT, if you are in an urban setting, it is loud. And if you are considerate, you probably don't want to do that early in the morning or late at night or even when people are around. It's loud (I think I said that?). But it is glorious and does not make the car sound like a "ricer". It was well worth the upgrade and highly recommended, if appropriate for your situation.

The installation was easy and fit was spot on. Not too noisy when zippin around town but will make some noise if you want! Looks a lot better also. Happy I waited. Availability could have been better.

Delighted with this muffler. Makes all the right noises and doesn't drone. Really comes alive from 4500-6500 rpm, get a few pops, maybe a crackle, when slowing. Glad we got this one!

This is the exhaust to get, full stop. It's quiet at cruising and under light throttle, little to no drone at all at higher RPMs and constant speeds and can get fun and noisy when you bury the throttle. Definitely adds a nice character to the exhaust sound. I actually am surprised at how quiet it is without any baffle in it! In my car under 3500 RPM or so it's got a nice deep tone to it and above that it loses some of the deep tone and essentially amplifies the sound it previously had while also being less buzzy than before. I've only had it on for a few hours but I fully anticipate leaving the baffle out and it sounding even better as it breaks in some more. VERY pleased with the purchase and the help from Goodwin Racing prior to ordering.

Great fitment, car sounds amazing with the new exhaust. I have no engine or exhaust modifications besides the muffler and it sounds great with or without the baffle. Almost no drone in the cabin even with the hardtop (notice a little under load going uphill around 3k rpm, but none while cruising). Highly recommend if you're on the fence about it!

Great way to make friends!

On my inaugural spin around the neighborhood some people out for a walk flagged me down! I stopped and they were like "hey, weren't you at the racetrack Friday?" I told them yes, and I was worried they were gonna yell at me about my loud exhaust. Anyway, they agreed it sounded good and I found some local gearheads.

This exhaust IS fairly loud at higher RPMs. At low speed and idle it's just a deep hum. However, if you're putting this on a stock NB you know you need those RPMs. Makes some nice pops and burbles occasionally on decel.

If you are in anyway on the fence on this product, do yourself a favor and just get it. Love the sound, it is not at all too loud for my taste. My opinion is that a little louder the better in a sports car that sometimes barely comes up to the lug nuts of other vehicles...
It actually took me longer to remove the old unit than it did to install this. I highly suggest the red polyurethane hangers. I used liberal sprays of white lithium grease.
It's a quality product and I am once again 100% satisfied.

When I was on the hunt for a new exhaust it was extremely difficult for me to decide what options to pursue for a variety of reasons. Video footage of exhausts can never really compare to hearing it in person and everyone has different tastes. What may be loud and obnoxious to one person might be quiet to another.

With all that said, It's been almost a year ever since I've installed the Roadstersport 4 and it has been everything I have ever wanted. The way I see it, this exhaust enhances the sound of the car instead of trying to change it. It produces a confident and deeper tone with subtle burbles and the occasional pop. It is reserved enough to be comfortable but can be playful when you want it to be. Run it without the baffle.

Addicted to the gurgles and pops with top down, baffle out. Deep tone down low with nice growl when you step on it, more noticeable in lower to mid RPM range. Baffle is perfect for the longer drives and easy enough to add/remove. Fantastic exhaust.

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