2023 Subaru WRX Long-Term Update: Our love-hate relationship with the STI exhaust

Associate Editor Byron Hurd introduced to you the official Subaru performance accessories that we had installed on our 2023 Subaru WRX. And of them, the one I was most excited for, and anticipated would change the experience the most, was the STI muffler. For as fun and feisty as the WRX is, the one thing I felt it needed more than anything was some growl. Or snarl. Or bark. It was just a little too quiet for its vivid paint job and huge hood scoop. So what did I think when I went to go pick up the WRX for the first time from Byron, post-op?

“Oh no, I think we might’ve ruined our WRX.”

Yeah, the first impression, with barely any miles on the exhaust, wasn’t great. The WRX has a relatively high-rpm cold start routine, and it ends up bringing out the worst of the muffler. It’s extremely boomy from the cabin, especially right in that rpm range from 1,000 to 2,000 rpm where the cold start sits. So your morning quiet is broken by resonant humming all through the car. And the boominess never completely goes away. It crops up at other points in the rev band, and especially on off-throttle deceleration. 

There is some good news on this front, though. After putting on several hundred miles, the overall volume did come down a bit, seemingly after the muffler had “broken in.” It never went away, but it did mellow.

Even more good news, there are genuine positives to this muffler. Aside from occasional boominess, the exhaust tone is fairly clean and deep. And once it settles into the warm idle, it has a little lumpiness like you’d hope from a boxer engine. The extra volume also is welcome for rev-matching, as Road Test Editor Zac Palmer noted, and generally is fun when driving the car hard.

There are two other important things that this muffler manages. First, it’s quite civilized on the highway. That boomy start-up had Hurd and me worried, but we discovered that it’s tuned just right to be quiet (just a little louder than stock) and drone-free at highway cruising speeds (60-80 mph). So you won’t go deaf after hours on the freeway. Second, it’s weirdly quiet from the outside. We don’t know how, but the exhaust almost sounds louder inside the car than outside. You can feel like a hooligan while driving, but without drawing the ire of your neighbors.

Oh, and the tips are sharp. The trapezoidal tips are unique and have crisp stamping, particularly the STI logos.

So yeah, in the end, the muffler is a slightly mixed bag. It gets pretty noisy inside, annoyingly so at times, but in some critical ways, it still manages to be livable. So we really can’t recommend racing out and buying it, nor can we say to stay away from it. Worth noting is that Subaru makes no claims to horsepower gains, which makes sense, since it’s just the resonator and tips, not any other parts of the exhaust, nor does it come with any revised engine tuning. And $1,139.95 is a decent chunk of change, even if it’s not going to void your warranty. Weigh our pros and cons against your priorities, listen to the video sample, and make your decision from there.