Reviews: Agency Power Muffler, Vivid Racing Tune, Circuit Werks Cat-Bypass, Headers

[onewhippedpuppy]

I haven’t seen much feedback on these products, so I wanted to give my personal experience. All are on a 2003 Boxster S with 80k.

Step 1: Agency Power muffler. Based on the pictures, feedback and videos online from other Porsche products, and some insight from Pelican BBS member porsche4life who works at Vivid Racing, I decided to give this muffler a shot. I also have a friend who had Vivid build a 600+ HP 996TT that he was very happy with. While branded as “Agency Power”, these exhausts are made by Vivid Racing whom I had never done business with. The 986 muffler is a more recent product, but they’ve been making other Porsche mufflers for years (just search YouTube). This muffler falls into the middle in terms of 986 muffler pricing, overall I think the price is quite reasonable. Cosmetic impressions were that this appears to be a well-made exhaust, with nice consistent welds, good overall assembly, and smooth mandrel bends. It was shipped quickly by Vivid and arrived undamaged and well-packaged. After removing the massive factory muffler reinstallation of the lightweight AP exhaust was easy, and just the muffler swap took 18.8 lbs off. Fit was literally perfect with the remainder of the exhaust being factory at this time. If I had to describe the sound in one word, it would be mellow. At lower RPMs the tone is lower, giving to a raspy howl at higher RPMs. Overall sound level is honestly very moderate, it is not significantly louder than the factory exhaust. Like most aftermarket mufflers on the 986 there is some drone under about 3,000 RPM, even lugging along in 6th gear on the highway I did not find it significant enough to annoy and I have certainly heard much worse. Though I was overall happy with the upgrade, even my wife agreed – “not loud enough”. So on to step 2……

Step 2: Agency Power muffler, Circuit Werks secondary cat bypass pipes, Fabspeed race headers (used). My goal with this exhaust upgrade was twofold, reduce weight and attempt to give my 986S a similar sound to my 1982 911SC Cab that is equipped with SSIs and a Dansk Sport. After this work was completed I’m happy to say mission accomplished! Let’s skip right to the good stuff, this setup sounds absolutely incredible. It has the nice staccato idle that is very reminiscent of an air cooled 911, the same raspy smoothness at lower RPMs, but transitions to an exotic raspy howl at higher RPMs. Absolutely, positively, incredible. The closest comparison I can find online would be videos of 996 GT3 Cup cars. Believe it or not the volume level during normal driving is actually quite good, you can short shift the car at 3,000 RPMs and never get a second glance in traffic. Highway volume is only slightly louder than stock, and there is zero drone. But none of that matters, because it is damn hard to stay under 3,000 RPMs. I would place this exhaust on the same pedestal as my dearly missed C63 AMG that sounded prepared to eat your soul, the Ferrari howl of my Maserati coupe with Tubis, and the timeless sound of my 911SC. As for the boring stuff, the installation was honestly no harder than installing the muffler. Fabspeed speaks for itself, and I was totally happy with the fit of the Circuit Werks secondary cat bypass pipes. While I normally default to a high quality manufacturer like Fabspeed, let’s be real – secondary cat bypass pipes are two simple mandrel bent pieces of pipe with O2 sensor bungs and a welded on flange, not worthy of the $500+ that Fabspeed charges. These three products all fit together perfectly, I couldn’t be happier. Final benefit, elimination of the secondary cat pipes and elimination of the factory manifolds saved another 15.6 lbs. Yes there are no cats, no it won’t pass emissions, and yes it will throw a CEL. So on to step 3…..

Step 3: Vivid Racing tune. At this point the tune was a no-brainer, because it’s the only certain way to eliminate the CEL from the cat delete. The Vivid upload tool shipped quickly, after receipt you have to download the Vivid software, plug into your car to download the factory configuration, send the file to Vivid, and they will send you back a custom tune. In my case I sent the factory file on a Saturday morning and had the custom tune by afternoon, very impressed in the turn time. In addition to being based on your specific factory software, the tune is optimized for your specific upgrades. Not really a big deal to me because I have a Durametric, but the Vivid upload tool will also allow you to read/reset the CEL, so that’s a bonus. Overall power delivery is much smoother and more linear, the car is more responsive throughout the entire RPM range, and there is more punch available everywhere. With the exhaust upgrade I felt like the only meaningful increase was in terms of sound, after completion of the tune it felt like a legitimate increase in terms of power. This is all 100% butt dyno for what that’s worth, but my wife also had the comment of “it feels faster”. Beyond the obvious need to eliminate the CEL, the tune is totally worthwhile and makes the car much more enjoyable to drive. I think the exhaust upgrades really needed a tune optimized for the new configuration, and I am totally satisfied with the end result.
So, final word on the topic, I’ve very happy with the end result of my exhaust and tune. The car is more enjoyable in every possible way, has far more personality, and finally sounds like a proper Porsche. Highly recommended!

A few pics:

[porsche4life]

Looks great and sounds great Matt! Glad you like it!

[stealthn]

Good write up, I guess what I don't understand coming from a Cayman is doesn't the muffler eliminate the secondary cats? They are in the muffler in the Cayman.

[porsche4life]

Matt, Correct me if I'm wrong, but I believe on the 986, there is only the primary cats, which are between the header and the muffler.

[onewhippedpuppy]

On the 986.2 there are cats that are integral to the exhaust manifold, and then the secondary cats that are built into the pipes between the manifold and the muffler. So replacement of the muffler alone does not actually disturb any of the factory emissions control equipment.