"Is this a hybrid" my friend asked jokingly as I floored it, hitting the rev limiter in my new Subaru WRX. I told myself I'd just keep the car stock, but deep down I knew I couldn't forever. We all want some sound from our cars. We want them to sound alive and angry when we really get on it.
An axle back exhaust system is a more affordable way to make your car sound louder compared to full catback exhaust system, and it's easy to install with just a wrench and some ramps, and doesn't require tuning.
There are a couple of different kinds of axlebacks. Some are called "muffler deletes," and as the name suggests, this totally replaces the mufflers with pipe. There are also axleback systems that have mufflers that are smaller than the factory ones and quiet the car down just a bit. Muffler deletes are still fairly quiet when used with the stock j-pipe, so we think best exhaust for the 2015-2020 WRX or WRX STI, if you just want to keep it simple.
We've reviewed some of the most popular axle back exhausts, including muffler deletes, for the WRX and WRX STI to help you pick the right one.
READ ALSO – Best Catback Exhausts for 2015-2020 WRX / STI
Mufflers: none
Exhaust Tips: 3.5 or 4 inches, double wall
Noise Level: 💥💥💥💥💥 (5/5)
The stock mufflers on the 2015-2020 WRX are gigantic, bigger than my head, and there's one on each side of the car. The most obvious solution is to get rid of them, if you want your car to be louder.
The Remark Muffler Deletes a 3.5" or 4" double-wall stainless steel tips and give the back end of the car a subtly higher-end look. Removing the mufflers entirely may sound extreme, but with the stock downpipe and midpipe left in place, these cars stay reasonably quiet until you step on it and really bring the RPMs up. This axle back overall feels very high quality, and bolts on easily in place of the stock mufflers.
If you want the most sound from your exhaust as possible, this is the way to go. Cold starts are deep and bassy, and the car will really scream when you rev it up. You'll hear pops and crackles uninhibited by any mufflers. While it's quite loud on a cold start or under heavy acceleration, it's quite tame under normal driving. This is how your car was meant to sound, whether you have the WRX with the new FA20F engine or the STI with the EJ257.
If you want something that stands out a little bit more, then Remark's muffler delete also comes in a version with burnt titanium tips. This is a premium finish that costs a bit extra, but if you're the kind of person who thinks every detail counts, you may love this axle back.
Mufflers: none
Exhaust Tips: 4 inches, double wall
Noise Level: 💥💥💥💥💥 (5/5)
CNT Racing offers a muffler delete for the WRX, including 4" double wall tips. This axle back is made from stainless steel, and includes replacement exhaust gaskets.
The large tips fill out the space in the WRX's diffuser nicely, filling in the space left by the stock exhaust tips, and you also get rid of the unsightly mufflers. These exhaust tips look so good it makes you wonder why Subaru didn't ship the car that way.
Mufflers: none
Exhaust Tips: 3.5 inches, double wall
Noise Level: 💥💥💥💥💥 (5/5)
ETS offers a muffler delete axle back exhaust system for the 2015+ WRX/STI. They make a burnt tip variant, as well as plain stainless steel. The burnt tips add a nice subtle flair that will be sure to make your car stand out from the crowd. While these demand a premium price compared to most of the other options, these are very high quality.
Mufflers: 4 inches
Exhaust Tips: 4 inches, double wall
Noise Level: 💥💥💥💥 (4/5)
The CNT V3 axle back exhaust system is an excellent choice for those who'd still like to have mufflers on their WRX, but without deadening the sound by much. The 4" mufflers will allow your exhaust to flow freely, help to eliminate drone when driving on the highway, but still give the WRX some more much-needed exhaust sound. Its 4-inch tips will add some aggressive styling to the rear end of the car. The CNT axleback is available with either plain stainless steel or burnt blue tips.
Mufflers: none
Exhaust Tips: 4 inches, double wall
Noise Level: 💥💥💥💥💥 (5/5)
Another great muffler delete for the WRX, for when you just want to get rid of the mufflers altogether. The SRS axle back has large 4" tips, to fill the extra space in the diffuser and give the car a more powerful look. This muffler delete will make your car sound great, is easy to install, and won't break the bank.
Mufflers: 4 inches
Exhaust Tips: 4 inches
Noise Level: 💥💥💥💥 (4/5)
MAPerformance is one of the biggest names in the Subaru modding world, known for their excellent quality parts and off-the-shelf tunes. Their muffler delete for the WRX is expertly welded with 3.5" inch tips, perfectly filling up the space around the exhaust tips. They come with double walled tips and are available in either stainless steel or burnt blue.
Mufflers: none
Exhaust Tips: 4 inches
Noise Level: 💥💥💥💥💥 (5/5)
Although we'd recommend the Remark muffler delete first, the Nameless muffler delete is also an excellent choice that many Subaru WRX owners have decided to go with. These are similar in design to the Remark Muffler deletes, but the tips are shorter, and the exhaust hanger is more clearly visible when installed.
Mufflers: 5 inches
Exhaust Tips: 3 inches, double wall
Noise Level: 💥💥💥 (3/5)
Nameless is a top choice for Subaru axle back exhausts in terms of popularity. They offer a few variations of the axle back, either as a muffler delete or with various different sizes of mufflers.
The muffler delete is a great choice, but if you want something a little tamer, Nameless has got something for you. The 5" mufflers are much smaller and less restrictive than the stock mufflers but will keep the volume down and help prevent drone.
Mufflers: none
Exhaust Tips: 3.5 inches
Noise Level: 💥💥💥💥💥 (5/5)
Magnaflow also makes a muffler delete for the 2015-2020 WRX and STI. It has double walled 3.5" tips, similar in design to the other axleback options. Magnaflow is a trusted brand, manufacturing mufflers and other exhaust parts for almost all makes and models, making this a safe choice for a quality axle back exhaust system for your WRX.
Mufflers: 5 inches
Exhaust Tips: 3 inches, double wall
Noise Level: 💥💥💥 (3/5)
The Rev 9 FlowMaxx Axleback Exhaust system is great choice for anyone looking to get some extra sound from their Subaru WRX. This exhaust system is available both as a muffler delete and with 5" mufflers. Like all of the other axle back options available for the WRX, it's easy to install with just a wrench, a jack, and jack stands. The 3" double-walled tips will add a subtle but high end look to the rear end of your car.
FAQs
What is an axle back exhaust system?
An axle back exhaust system, as the name suggests, it the part of the complete exhaust system behind the rear axles. On the 2015-2020 Subaru WRX, the stock axleback system has a large muffler on each side of the car. An aftermarket axleback replaces this, either giving you smaller mufflers or no mufflers at all, making the car louder.
What model years are these axleback sytems for?
These exhaust systems work with all Subaru WRX and WRX STI models from 2015 and up, so that includes the 2015, 2016, 2017, 2018, 2019, and 2020 model years. The factory exhaust system for these models has been unchanged, and aftermarket systems for all of them are the same, just simple bolt on parts.
Do you need a tune for an axle back exhaust?
No, you don't need a tune for an axleback exhaust or muffler delete. You can go as far as installing a catback exhaust system with no tune. It's only when you get to the downpipe that you need a tune, since then you're affecting the readings of the oxygen sensors.
What does axle back mean?
An axle back exhaust refers to the section of the exhaust that's behind the rear axle. There's the headers, the downpipe, the midpipe, and finally the axle back section of the exhaust.
Does an axle back add horsepower?
An axle back won't add horsepower, at least anything you'll notice. Some sources claim picking up around 3-6 horsepower with dyno testing, but in general it won't add any meaningful power, just sound.
Is it a catback louder than an axleback?
It depends on the catback and axleback being compared. A muffler delete will be louder than a catback that has a resonator and mufflers, but there are many catbacks louder than muffled axle backs.
Does installing an axle back void your warranty?
No, installing any axleback or muffler delete won't void your warranty. This type of modification doesn't affect how the car runs in any significant way, and can't cause anything else to fail.