Hi Everyone.
This is my first post here but I've been lurking and learning for a little while now. I recently completed a project on my boxster that I wanted to share with everyone; my way of giving back for all of the knowledge I gained (and money I saved!)
I have an 06 Boxster S which I love dearly, mostly stock aside from a short throw shifter. However all of my friends say it sounds like a sewing machine, and It definitely could use some extra bark. I had spent a ton of time researching exhaust options and I ended up looking at either the Carnewal exhaust mod, or a borla exhaust system. The borla system seemed to be around $1600 (which I really didn't want to spend that much if I didn't have to) and, although the carnewal exhaust sounds great, I wasn't thrilled about shipping it out. Furthermore, I really liked the idea of the factory PSE where you can turn the exhaust on and off since I take very long drives with the car, and with the top up any excess exhaust noise would be unbearable (and my wife would likely refuse to drive with me).
I was rather intrigued by people doing the "free sleeve" mod, but it also seemed slightly ghetto. Furthermore, I had tossed around the idea of replacing the exhaust tip to finally get rid of the dreaded T outlet, however I couldn't justify spending $500 to do so. So I kinda go to thinking, what's stopping me from placing a valve, on the muffler crossover pipe? And that's exactly what I did.
Now full disclosure, I am a mechanic with my own shop, so this likely isn't for the weekend DIY'er. However if you have access to a welder and have some decent ability, this mod isn't impossible. I owe much of my success on this mod to delman1012 for his advice on the wiring and the great write up and diagram he posted here:
https://www.planet-9.com/987-cayman...7-cayman-and-boxster-modifications/109558-pse-retrofit-success-06-cayman-s.html
So basically I used the switching valve he recommended, along with a latching relay, mounted in the trunk as he recommended. This also required me to run an ignition switched power wire and the exhaust button trigger and indicator wires into the engine bay. All in all it's not too bad and there is a nice grommet at the top of the firewall to snake through. One of the hardest parts was finding the correct switch for my car which ran me $100. Furthermore, you need to add 2 extra wires to the harness, which are $70. I'm cheap so F that noise. I decided instead to open up the switch assembly and I drilled a small hole in the bottom. I was then able to solder directly to the terminals inside the switch and run the wires out the bottom instead.
After that I found a decent vacuum operated exhaust cutout valve on ebay for $120 and got some cheap exhaust tips from Autozone. They clamp onto smaller stubs that come out of the mufflers. This allows me to adjust the angle, length and spacing of the tips, and change them if they get dirty or if I want to go bigger.
As far as the engineering is concerned I removed both mufflers and created a T out of pipe replace most of the crossover pipe between the mufflers. I had to cut about 2" off each crossover pipe and just managed to squeak the dump out he bottom. It is tight, but there is room. The key is finding the correct stainless tight radius 90* for the outlets. Luckily my uncle is a plumber and has access to a ton of pipe so he had some stuff kicking around. As you can see the alignment is near perfect and it makes room for the dump to go between the 90* outlets.
As far as the sound is concerned, it's definitely a little boomy from idle to 3K rpm. The sweet spot is really from 3k rpm to redline, which likely isn't surprising considering the DME is programed to disable the factory PSE at lower engine speeds. It is possible to adjust the length of the rod on the vacuum valve to change the amount it opens (similar to sliding the sleeve on the "free"mod). However I like the distinct difference in tone since I have the option to turn it on and off at will.
Lastly the beauty of the whole thing is it's reversible. The cutout valve is only clamped onto the crossover pipes so, all you have to do is remove it and clamp in a straight section. Granted I cut down the muffler outlets to run the 90* exits, but that could be reversed if you really wanted. You can't notice anything unless you really crouch down and then you can just barely see the bottom of the cutout. Moreover, If a used PSE ever shows up for the right price, I could upgrade and I already have it pre-wired.
