The SpeedTech 996TT X-cellerator cross-flow/X-Flow exhaust was designed to offer the discerning Porsche enthusiast the ultimate exhaust system with a number of performance and sound options in one modular platform.

CROSSFLOW or X-FLOW DESIGN - By combining the exhaust pulses from both sides of the Porsche boxer motor with an "True-X" at the center of the muffler (internal crossflow design), we have developed a unique, exotic sound that has to be heard to be appreciated. Our trademark sound is well known and highly respected throughout the industry.

DESIGN OPTIONS - The X-cellerator system includes catalytic converter bypass pipe and muffler bypass pipe options resulting in four possible exhaust configurations:
Our modular design uses V-Band couplings which allow for quick and easy swaps between the various sound and performance levels. This versatile design is very easy to use and offers quick installation and/or swaps.

PERFORMANCE - The SpeedTech X-cellerator cross-flow system eliminates approximately 25 pounds of weight (full system w/ cats) compared to the Porsche OEM exhaust. Additional weight savings can be realized with use of the off road configurations. Whether lap times or straight line speed is your goal, the weight savings will help yield quicker track times. Faster track and ¼ mile times, better everyday performance and the pronounced engine note will provide an enhanced driving experience for all types of uses.

Our free flowing, straight through design, along with proprietary Hi-Flow 100 cell “Hi-Flow” catalytic converters will improve the performance of your Porsche 996TT. Our 100 cell catalytic converters offer the extremely quick turbo spool, along with increased torque, higher horsepower and much crisper throttle response vs. OEM or even 200 cell aftermarket cats!

All components are constructed of T304 stainless steel and our
mufflers are packed with stainless steel wool for years of trouble
free performance, even under extreme use conditions. This is a
very well built, top of the line exhaust system for the discriminating enthusiast and very fitting for the Porsche turbo.

TIPS - We offer several tip options to appeal to a variety of tastes. Each tip option is pictured to the right. They include:

SOUND - The SpeedTech X-cellerator X-flow system delivers a phenomenal, exotic, high end car sound that the majority of Porsche owners desire and appreciate. Many of our customers have tried several other exhausts (some up to 5) before discovering the SpeedTech X-cellerator system. This system has received numerous unsolicited accolades, many of which are displayed on our testimonials page. The bottom line is that this system sounds fantastic and offers all options one could desire in a performance exhaust. It is available in either a full 3” version (loud), a 2.5” muffler version (quiet) or a Competition "X-Pipe". All SpeedTech exhausts exhibit our trademark SpeedTech "X-Flow" engineered exotic sound.

2.5 - Our 2.5 "quiet" version is extremely quiet in the cabin while cruising at low RPM’s and allows for easy cell phone usage, conversation and music enjoyment. Yet under acceleration it emits a very sporty, wonderful, high-end tuned sound. The perfect combination and aggressive enough for the majority of turbo owners! When optioned with the muffler bypass pipes, the 2.5 becomes a lightweight, full 3” straight pipe system for track use! A competition 2.5 X-Pipe can also be fitted for a loud exotic sound with no drone.

3.0 - If you desire a loud, aggressive sounding system, the 3.0
version is for you. The assertive tone on start-up is followed by a

dominant cup car like wail at WOT. A true race car sound for the
street. The full 3” design will provide unrestricted flow, even on
the most powerful built cars, as well as a stock car. The 3.0 X-cellerator muffler is deeper in tone and the 3.0 X-Pipe provides a high pitched Italian exotic style wail.

Please take a moment and listen to our videos below and hear
all systems for yourself.

We offer a lifetime warranty of manufacturing defects for the
original owner. The SpeedTech X-cellerator is designed, tested and manufactured in the USA .

It is important to understand that not all “X-Flow”designs are the same - We tested all forms of "X" design exhausts on the 996TT during our 996TTproduct development , including:

This represents all common X-Flow designs. After extensive testing, we chose our internal “True-X” design as offering the best quality sound on the 996TT, the goal being to eliminate unwanted resonance and achieve a desirable exotic type sport sound. Our proprietary "X" design produces a more refined, tuned quality and was best at eliminating unwanted resonance (drone). SpeedTech has made the "X" design famous for offering a fantastic sound on twin turbo Porsches and we feel that with our innovative and unique internal “X” design, we have developed the finest sound available for the 996TT. Our X-cellerator system has been chosen by many customers over several competitors in direct testing, some systems costing almost twice as much. We found that by mixing the two banks of exhaust gasses inside the muffler, as well as, at the "X", we achieved the best possible sound from the 996TT. This design is exclusive to SpeedTech, which allows us to reach a pitch that the other designs can not match, resulting in what many claim to be the best sounding system on the market.

As part of our R&D, we extensively tested numerous tip designs to produce the perfect exhaust note. Our final SpeedTech "Sound Engineered" tip design was developed to provide the most refined exterior note combined with unprecedented interior comfort for a performance exhaust. There is no substitute for this type of extensive R&D with exhaust design. It takes more than fabricating a good looking exhaust to achieve the proper sound. The combination of our internal "X" cross-flow muffler with our sound engineered tips results in a unique sound and comfort that our competitors simply can not match. We do offer an OEM tip option as a base system, but we recommend our SpeedTech tips as they are harmonically engineered to provide the best possible sound from our "X-cellerator" systems.

There are many companies copying the SpeedTech X-design principal today, yet none have achieved the unique exotic sound or the quality of the SpeedTech exhaust sound. Often they use poor fitting, improperly sized or off the shelf mufflers & components, combined with untested X-designs that drone, hang too low and/or utilize inferior muffler packing materials. The SpeedTech X-Flow muffler is a complete, ground up, in-house design that emerged from extensive developmental testing, while seeking to design the best possible exhaust system for the Porsche 996TT. You will never find a SpeedTech 996TT X-cellerator muffler or muffler component selling under another name because we produce every system from scratch and none of the components are “off the shelf” or available anywhere else. Even our catalytic converters are hand made in house and are not "off the shelf" units. Many of our competitors exhausts end up for sale very quickly after purchase and often the decision is then made to purchase a SpeedTech. We have seen this repeatedly and our advice is to "make the right decision the first time and don’t waste your time and money on a questionable product"....only to end up with buyer remorse and replacing it a few months later. When you purchase a SpeedTech system, you are purchasing a one of a kind, superior sounding and performing exhaust, designed by long time Porsche enthusiasts. We strongly feel there is no better choice. And we guarantee it! (see sound guarantee for details)
porsche 996tt exhaust
100 CPI Hi-Flow
Catalytic Converters
Speedtech X- cellerator 2.5 "Quiet" Exhaust with 2.5 Dual Tips
4" Round "Sound Engineered" Tips (Recommended)
2.5" Dual Tips (Optional)
Re-Use OEM Tips (Standard)
Cut-Away View of SpeedTech Internal "X" Design
Pricing / Options (and VIDEO)
Includes 100 Cell Hi-Flow catalytic converters (3" out), 3: mid-pipes, 2.5” / 63.5mm muffler, OEM tip outlets, all required hardware, decals and installation instructions. Modular design for ease of use and installation. Our most popular selling system!

2.5 "Quiet" X-cellerator Exhaust System
Includes 100 Cell Hi-Flow catalytic converter, mid-pipes, 2.5"/63mm or 3.0” / 76mm X-Pipe (no muffler), all required hardware, decals and installation instructions. Modular design for ease of use and installation. Can be substituted with X-cellerator mufflers. Best 3" X-Pipe design available for sound quality/lack of resonance! Also available in 2.5" sport sound level for the same price.

2.5" or 3.0" Competition" X-Pipe Exhaust System
Our 100 Cell Hi-Flow catalytic converters were100% designed by SpeedTech and manufactured "in house". The turbo flanges are bored, ported and flow matched to the 996TT K-Series turbos for maximum performance and improved spool. These are not "off the shelf" universal cats or cheap import converters, but rather high quality substrates manufactured in the USA. Fit all X-cellerator systems.
SpeedTech Hi-Flow 100 Cell Catalytic Converters
Our catalytic converters bypass pipes can be substituted for converters during race, track or off-road events where light weight, improved spool, hi-flow, and race fuel are desired. The turbo flanges are bored, ported and flow matched to the 996TT K-Series turbos for maximum performance and quick spool. Fit all X-cellerator systems.
SpeedTech Catalytic Converter Bypass Pipes
Our full 3" muffler bypass pipes can be substituted for mufflers during race, track or off-road events where light weight, improved spool and maximum performance is desired. The turbo flanges are bored, ported and flow matched to the 996TT K-Series turbos for maximum performance and quick spool. Fit all X-cellerator systems.
SpeedTech Muffler By-Pass Pipes
SpeedTech 2.5 X-cellerator Exhaust Video
SpeedTech 2.5 Cold Start Video
SpeedTech 2.5 Catless "RACE" Video
SpeedTech 3.0 - X-Pipe Video
SpeedTech Hi-Flow headers constructed of T304 stainless steel enable additional flow capacity for modified cars. Features include Hi-Flow design, smooth merged collector
and perfect fit for maximum performance and quick spool. Fit all X-cellerator systems.
SpeedTech Headers
Add a Softronic Tune!
Add a Softronic Tune!
Tip Options
ast1003039.jpg ast1003038.jpg ast1012036.jpg
SpeedTech 3.0 - X-Pipe Video - GoPro
Several Choices. For all X-cellerator systems, choose from our Sound Engineered 2.5 or 3.0 round tips, 2.5 or 3.0 dual tips, GT2 RS Style 3.0 tips or OEM style tips. Our OEM style tips are a perfect upgrade for 996TT OEM exhausts or any exhaust that uses the OEM tips. They also fit our X-cellerator series exhausts when ordered with the OEM tip option. T 304 stainless seel construction with mirror polished finish.

OEM x54 sTYLE tips - $ 349.95 *require outlet pipes w/ X-cellerator system
2.5 Dual Tips - $ 595.00
3.0 Dual Tips - $ 495.00
GT2 RS Style 3.0 Tips (2.5 or 3.0) - $595.00
*OEM Outlet Pipes for X-cellerator system - $349.00
SpeedTech Tips
SpeedTech 2.5 - X-Pipe Video - GoPro
  1. 0 X-Pipe -
Hi John,
I had the 3.0 X-pipe exhaust installed on my ’04 911 TT Cabriolet last Friday and let me tell you I am one happy camper. You tube video’s and sound clips just do not do your system any justice. I knew the X-pipe was something as soon as I went to pick up my car and my guy pulled me aside immediately and had a little grin on his face. Originally he seemed apprehensive because he never heard of Speedtech and threw it off as some internet sensation. But now he is a believer.
He fired it up and all I could think of was WOW so this is what my Turbo was meant to sound like. The sound was raw, unadulterated and like nothing I have heard on the street. As I left the shop with a huge smile I noticed my Porsche tech standing at the end of the drive so he could listen as I drove off. My immediate observation driving the car was the noticeable increase in responsiveness and low end power from only a simple exhaust upgrade. Then I opened it up for the first time and, holy cow, the exhaust was so aggressive and loud, reminded me of the Cup cars I recently saw at the local race track. What an impressive piece.
The next day I went to a local informal gathering of Porsche enthusiasts. As soon as I turned the corner heads began to turn to see what was coming in. I parked and a number of 911 owners came over to praise the sound and ask what exhaust I had. I even had a number of guys stick around until I left so they could follow me on the road and have a listen. I spent the whole weekend cruising, enjoying my “new” car and looking for underpasses so I could really crank it up. What a pleasure. My family, including wife and 4 and 5 year old sons love the sound and can’t get enough of it. I need to drop the top so they can hear it that much more. The sound only gets better each time I go out for a drive.
From the cold start to the “gurgling” on deceleration to the aggressive and intimidating sound at WOT, we love it all. Thank you and your team for creating such a fantastic piece. I couldn’t find a way to put this under the testimonials on your website, so I will leave it to you if you wish to do so.
996TT Customer Comments
996TTS - 2.5 Quiet

I recently bought my 996 Turbo S and saw a few posts by John on Rennlist. I sent him a message to simply inquire about the benefits of changing my stock exhaust to a Speedtech. John responded immediately and was both extremely knowledgeable and helpful. We spoke generally about upgrades and it was helpful that John had a TT and has invested in many upgrades. It was really a pleasure to speak to John and to ultimately do business with a small American fabrication company. I decided on the 2.5" quiet exhaust based on John's recommendations for my needs. I am very pleased with the new sound and openness that my Porsche now possesses. It is a very different car and much more throaty and responsive. My IPS installer said that he has installed several competitive exhausts ranging from $3K - $10K and that this exhaust was as well made as any he had seen, easy to install, and sounded great! I highly recommend Speedtech to anyone considering this upgrade. If you have any questions, John can assist you. During the decision and purchase process, John often responded to my messages well into the evening EST. Highly recommended!

John K., GA
996TT 2.5 "quiet" -

Having purchased and installed my 2.5" quiet system from John in May 2010, I could not be more satisfied with both the product and the service from John and company. On the sales side, John was patient in answering my apprehensive questions (having unfavorable 993 drone experiences with other aftermarket products). During my install, when a question arose, John returned my call on the weekend (how many vendors do that??).

The product receives unsolicited comments on its sound quality from even non-Porsche owners (the most recent just a few weeks back). The spooling whoosh is cool to hear, the WOT invigorating, and the butt-dyno gives two thumbs up as well (but not up the butt ).If you are on the fence about this product, pull the trigger and move forward; you will be sorry you waited so long...Thanks John !!

Guy N, CA
996TT 2.5 "quiet" - John, You guys have created one sweet-sweet sounding exhaust, my man. I mean sweet!!! Its about as close to a GT-3 as you could possibly get. And like you said - no drone. You can clearly hear the turbos when its not screaming at WOT. Either way - it sounds glorious. Thanks a bunch. It truly sounds better than I thought it would.

Steve, TN 996TT
Sound waves mix internally AND at the "X" for the best X-Flow sound Characteristics
3" dual Tips (Optional)
Porsche 996 Twin Turb/ GT2 X-cellerator
Exhaust System (2001-2005), 3.6L
2.5"/63mm quiet or 3.0"/76mm
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Still loving my 2.5 xflow. Best by FAR of the five systems I've had. Anybody on the fence you won't be sorry. And happy to support great people who stand behind their product.

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