The base WRX sounded very good with the factory equipped exhaust system. Subaru left out the mid-pipe resonator (there is a resonator in the downpipe just before it meets the mid-pipe) so volume was decent--just enough dBs to let you know it was there but not enough to wake the neighbors...until you started driving, then: Total silence. Wind noise and sound deadening made it impossible to hear what the engine was doing. No intake noise. No exhaust note. If you have the windows up or the radio on exhaust noise was imperceptible. On the race track not being able to hear the exhaust was odd and made driving a little trickier. I really had to monitor the tach to see where I was rather than relying on my ears to determine shifting points. I'm sure it didn't help that I was very new to the car and still learning its language.
The stock components are well made and really light weight, coming in at 38lbs for the 2.5" mid-pipe and two mufflers (2.0" inlets from mid-pipe). The mid-pipe hanger has moved ever so slightly from previous gen cars, but there are still five of them. Undo the six bolts and the five hangers and the OE CBE is off. Super easy. The Perrin Brushed Steel, Quad Tipped Catback PSP-EXT-347BR
is very robust--you all know this already, it's been around for several years now. Install is easy and the same as on the 08-14 cars, except getting the alignment right is a little trickier thanks to that one relocated hanger. Because the Perrin is 50lbs I opted to swap out the OEM rubber hangers with Cobb 511312 Urethane Hangers
. The Cobb hangers are firmer so the added weight won't induce premature sagging. Pix below are of the various exhaust components on a scale....missing is the OEM mid-pipe because I had to weigh myself, then weigh myself while holding the mid-pipe so I wasn't able to get a shot of the scale... trust me...the OEM mid pipe is right at 12lbs.
The Perrin CBE works on the 15 WRX and STI because of the three slip joints and the shape of the y-pipe. The slips allow for a decent range of adjustment and fine tuning so you can get the four tips centered in the openings. So, for install leave all of the slip joints and the one v-band loose. You need to remove the OE donut gasket from the downpipe to mid-pipe joint and replace it with a Perrin-supplied flat gasket...you can snug this junction up completely since there is no adjustment gained by leaving it loose. The second half of the mid-pipe attaches using a slip joint--make sure you put the clamp on before slipping the mid-pipes together and you consider the angle and direction you put it on with...this one comes really close to the driveshaft so if you do it wrong you will have a bad time. There is a hanger at the back end of the mid-pipe near the v-band, attach the hanger to the car then to the pipe.
After the two halves of the mid-pipe are up we moved on to the mufflers. There are two hangers per side and the one on the outside is a bit of a pain to reach, even on a lift. Again, we put the hangers on the car then hung the mufflers from them. Don't worry too much about where the tips hang yet. The Perrin y-pipe has a slip joint on either tail of the y—Perrin ships them all slipped together so you need to undo them and put the clamps on then slip them back together before putting the y-pipe in place between the mid-pipe and mufflers. Again, consider the angle and direction of the clamps before suring them up later on--don't bother tightening them yet. With the slip clamps in around the joints put the y in place. We snugged up the v-band first leaving it loose enough that we could rotate as needed the put the 2"gaskets in place between the y and mufflers. Tighten the four bolts (two per side). Now comes the tedious part of aligning and tightening.
We worked positioned the tips where we wanted them--centered in the openings and sticking out just slightly--then tightened the slip clamps around the y tails, then v-band , leaving the mid-pipe slip for last. It took a few times to get this right. Most difficult was getting the right side muffler in the right place as it wanted to hit the car at the forward edge. Took a bit of manipulating of the slips but it came out really nice.
I've now got 200ish miles on the Perrin CBE and can say the tone and volume is really pleasant...Perrin has a resonator in the mid-pipe, I imagine a system without this would be quite loud. No highway drone. No rasp. Even with the factory elh there is enough rumble to let you know there's a boxer under the hood. We also swapped the OEM intake filter for the Perrin filter. No noticeable performance gains from the intake and exhaust. But, the sounds are so much better. We will be going to a dyno in the week or so to get some numbers (we'll swap exhaust and intake back to stock for a baseline).