As cool as a lumpy camshaft may sound, nothing beats the noises that a turbocharged car makes. From the whistle of the turbo spooling up to the blow-off valve venting to the distinctly muffled exhaust note, there’s nothing like it anywhere else. Best of all, it’s extremely easy to amplify these sounds just by installing a few aftermarket parts.
We’ll show you how.
The subject vehicle for our sound amplification test is a 2003 Subaru WRX. It’s a hot choice among tuner cars with its tenacious all-wheel-drive and healthy 227 horsepower packed in a little sub-compact. And then there’s the sound–from the factory, it sounds good, but quiet.
An aftermarket exhaust will unleash the legendary boxer rumble and make it sound just plain mean. To open up the exhaust note, we did some surfing at SummitRacing.com and picked out a MagnaFlow exhaust system. MagnaFlow offers two different systems for early WRXs: one is a JDM-style system where the muffler is canted to the outside of the car (known as the JDM kick), and it features a 3-inch diameter pipe. The other, and the one we chose (MPE-16661), is a 2.5-inch diameter pipe with a straight muffler exit.
We also replaced the downpipe, which is the exhaust pipe that comes directly off the turbo and connects underneath the car to the cat-back. The factory downpipe is a bit restrictive, and with the WRX turbo’s integrated wastegate, the excess exhaust is dumped right into a wall and forced to find its way off to the side and down the exhaust. Aftermarket downpipes generally come in two designs: a bellmouth where the exhaust pipe is flared wider than stock to offer improved flow from the wastegate, or a divorced configuration where there are separate pipes for the exhaust and wastegate that merge a bit later down the pipe. Both are improvements over the stock piece and usually larger in diameter to support greater power levels.
For the downpipe, we opted for Injen’s catted downpipe, which is a bellmouth design with an integrated catalytic converter. Our subject WRX has racked an impressive 197,000 miles on the odometer, and the P0420 code that had been triggered was telling us it was time to change out the converter.
Another key element to making your WRX sound and perform better is a cold-air induction system like the K&N Engineering kit we ordered from Summit Racing. Factory induction systems have to be extremely quiet to satisfy the average consumer and pass drive-by noise standards, among other things. Opening up the intake tract often increases the induction noise, but that’s a good thing in our case. K&N offers a number of types of intake systems for the WRX, and we chose the short-ram-style Typhoon series.
In addition to giving the Subaru a serious growl and unleashing the whistle of the turbo, these modifications have also managed to virtually eliminate the notoriously bad turbo lag that plagues the 2.0L WRX. This makes the car easier to drive and allows the turbo to spool up faster, thus increasing power at a lower rpm.
While these modifications are relatively easy to accomplish, you’ll want to have a few things handy just in case you encounter a few fairly normal issues. When working on any exhaust system, you’ll want to use some penetrating oil ahead of time to help break the bolts and nuts loose. A small propane or MAP gas torch can also be helpful as heat can often free up rusted fasteners better than the oil.
The exhaust system on our subject vehicle was pretty old and fairly crusty, and even though the factory downpipe had been off in the last year, we still encountered a couple of troublesome fasteners that snapped off or needed to use a tap and die set to cut fresh threads in. The exhaust parts do include some new hardware, but some of the factory fasteners are reused as well. If your exhaust is all original, you may want to have a stock turbo-to-downpipe gasket on hand as well. Having to work through these possible issues is something to consider if you’re planning on doing the install in the afternoon and taking your guy or girl friend out later that evening!
Check out the photos and captions to see how easy these mods are to do, and be sure to watch the video below to hear the boxer growl!