Porsche 991 GT3 / GT3 RS Side Muffler Bypass Pipes (2014-2016)

$995.95 - $1,595.95
(2 reviews) Write a Review
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Optimized design that replaces the heavy and restrictive factory side mufflers for improved exhaust flow, increased sound and weight savings. 

Utilizing premium Helical valves along with the addition of O2 bungs, Fabspeed's Side Muffler Bypass Pipes provide the ultimate track solution for the 991 GT3 / GT3 RS. When accompanied with our new Long Tube Competition Headers, our Side Muffler Bypass Pipes allow the maximum amount of exhaust flow possible from the 991 GT3 / GT3 RS engine.


We chose to use Helical Valves on our 991 GT3 / GT3 RS track exhaust systems for their unprecedented quality - which have been proven by many OEM manufacturers such as McLaren, Ferrari, Lamborghini, and many more. Helical valves are an integral part of our Side Muffler Bypass pipes, opening and closing with precision to control the gas flow and optimizing engine back-pressure for improved performance. Helical’s extensive experience in high-volume OEM automotive applications has led to standard features such as an extremely durable pneumatic actuator, precision flat sealing faces inside the valve, stiffening ribs and high-temperature bearings at both ends of the butterfly spindle.


We relocated the O2 bungs from the collector of the headers to the Side Muffler Bypass Pipes in order to maintain factory-like functionality with our Long Tube Competition Headers - allowing them to read all cylinders while maximizing the performance of the collector. This design will replace our existing SMBP’s allowing you to upgrade to our Long Tube Race Header design at any time in the future.                                               


  • Fits all Porsche 991 GT3 / GT3 RS vehicles (2014-2016)
  • Highest quality Helical valves
  • Includes O2 bungs for factory like functionality when paired with Fabspeed Long Tube Competition Headers
  • Saves 34 lbs from the rear of the vehicle
  • Replicates aggressive CUP car sound for the street
  • 14-16ga T304 Stainless Steel construction
  • Simple bolt-on installation
  • All Fabspeed performance products are backed by the Fabspeed Lifetime Warranty

Click Here For Install Instructions for Porsche Homelink Connection For Valvetronic Exhaust Control

Warranty / Installation Guide


  • 5
    F1 srcream !

    Posted by johnm on 14th Jun 2017

    the fabspeed valved side delete pipe is perfect for the decibel adjustment when needed , it should take the edge when needed, like during the early mornings starts.
    Super easy to fit , and of course the quality is first class .
    The side delete is not as loud as you would imagine as the stock side muffler also has a straight through path when the valves are open , but it's the massive weight of the rear end has got to be worth a few horses ! well done fabspeed.
    and it sounds great !

  • 5
    Fabspeed Valved Side Deletes Installed

    Posted by Sean on 28th Jun 2016

    Since getting my RS I've been exploring the options for exhaust - basically the options I considered were side deletes and center delete. I ended up deciding on side deletes because of the weight and heat reduction properties of it. Weight reduction was a bonus - the primary benefit to me was to get all of that heat out of the rear of the car / tires / etc. I landed on Fabspeed based upon the recommendation of this forum, the valves and their good reputation / presence on Rennlist.

    The install was relatively straightforward. There are plenty of pics online of the bumper removal etc. It was basically the same process as the regular GT3. Remove bumper cover, remove heat shields and bumper bar, unbolt and remove center exhaust, remove side "suitcase" mufflers, reassemble. My 11 YO and I did it in the garage last night it took us 2.5 hours and was a wonderful bonding experience. This was the first time he's worked on the car with me where he has remained active and engaged the entire time. He was actually very helpful grabbing tools, holding things in place, etc. Made this install a lot of fun!

    We fired it up around 8 last night - And there is an immediate difference in sound. A low rumble on cold start. Time to go for a drive! We drove it about 8 miles. First - there is slight drone when the engine is lugged at 1800-200 rpms when cold. When the engine warms, this exhaust has zero drone, and really sounds fabulous. I'm still getting used to the different sound below 2200 - I will say at low RPM's (below 2200 or so) the center delete options sound better. However, with this mod, there is zero valve transition, which makes it much more linear in sound and a very good thing. Above 2200, this thing just screams. You get a few little burbles on downshift / over run which were a nice surprise. In terms of sheer sound volume, this is 15-20 pct louder than stock. Not at all overwhelming and, in my mind, the perfect sound level.

    I think it's a keeper - not too loud, no drone, weight reduction, heat reduction, valves functional and really great sound.