Maximum Power - Exquisite Sound - Precision Fitment

Subtle by design, the Audi TT Quattro stands out by blending in. Underneath the paint, the TT quattro is a serious driving machine with incredible potential. Though powered by the same 1.8T powerplant as a basic mk4 Golf, a modified TT quattro is capable of superior power, traction, and speeds. Without a doubt, the TT requires modifications of a higher caliber. Eager to raise the bar, 42 introduces our Audi TT 3" cat-back exhaust system.

A successful 1.8T performance exhaust may start with a 3" downpipe, but a proper cat-back can make or break your driving experience. Our 3" cat-back exhaust system for the 180Q and 225 Audi TT picks up where our 3" downpipe leaves off. The combination is an engineered exhaust system that yields maximum power, exquisite sound and tips that complete the performance look.

Starting at the final flange of our 3" downpipe, our 3" cat-back bolts up without modification using locking hardware and a double layer graphite gasket. A slight 3" mandrel bend tucks our straight through resonator into the heatshields away from road debris. A stubby hanger and a series of mandrel bends routes 3" tubing under the rear suspension to a CNC machined adjustable flange connection. Exiting the flanges, tight radius 3" mandrel bends allow exhaust gases to enter the rear muffler. Inside the rear muffler exhaust gases are divided into an opposing pair of 2.5" outlets. Tight radius bends and precision hangers position two stainless steel tips perfectly in the rear bumper.

Perfectionism is our obsession - reflected clearly by our exhaust tips. Our tips are pressed in-house from 304 stainless steel, welded and polished to a mirror finish. Beyond our tips, every raw material and component that goes into this system is carefully scrutinized before entering fabrication. Each system is assembled on precision tooling which ensures that every system fits exactly as intended. Every joint is carefully TIG welded and each system undergoes final inspection. This attention to detail is naturally what the TT deserves.

The sound is truly exquisite. At idle, the TT emits a suggestive rumble. At low rpms and cruising speeds the sound is sporty and refined. The exhaust opens up at full throttle and high rpms with a powerful tone and not a hint of rasp. Inside the car, the shape of the hatch and rear end design naturally amplify exhaust sound. With the rear seats installed the volume is minimal and the system does not drone. During testing we experimented with various resonator and muffler combinations before finding the perfect balance of power and sound. Scroll down to view our video sound clips!

Installation is simple, adjustable, and reliable. A permanent flange allows the system to bolt to our 3" downpipe. Precise design and fabrication routes piping clear of heatshields. Adjustable flanges allow further adjustment if necessary, sealed by double layer graphite gaskets and locking hardware. A pair of collars on each rear hanger lock the muffler in place. This means your tips will never slide out of place.

Pricing starts at $700. Complete turbo-back systems are available for 180Q and 225 models in additional configurations. All configurations can be purchased ceramic coated.

TT 225 3" Cat-Back - $700

TT 180Q 3" Cat-Back - $700

Our TT 180Q & 225 3" cat-back systems are specifically designed:

• to bolt-up to our 180Q & 225 3" downpipes
• as the rear portion of our 180Q & 225 3" turbo-backs
• to be custom fit to a 3" downpipe (custom or otherwise)
• to be used on heavily modified vehicles
  

Our TT 180Q & 225 cat-back systems are NOT designed:

• to connect to a stock 180Q or 225 downpipe
• to connect to a stock 3.2L downpipe
• to fit any 180FWD TT
• to fit any vehicle other than a TT with 180Q or 225 hardware

Fitment to our 180Q/225 3" downpipes or as part of our turbo-back systems is as easy as we describe. Fitment to a 3" downpipe not built by 42 requires welding of a 3" flange to the existing 3" downpipe at the correct location, angle, and rotation. Successful fitment of our 3" cat-back in custom applications is the responsibility of the owner. Fitment of our 3" cat-back to any stock downpipe or downpipe under 3" in diameter is not recommended by 42 and cannot be supported. There are reasons why we make specific recommendations. Please read our FAQ & Installation Instructions for detailed installation information.

If you're interested in a full turbo-back exhaust, we offer systems for the 180Q and 225 TT which combine these cat-backs with our 3" downpipes. Check them out! 180Q & 225 3" Turbo-Back Systems

180Q vs. 225 Fitment

We currently offer our TT 3" cat-back in two fitments - 180Q and 225. Each fitment is designed to bolt to our respective 3" downpipe using our CNC machined flanges. Fitment is specific to each model and each downpipe. Rumor has it that 180Q and 225 exhausts are interchangeable. Our experience proves that each downpipe terminates in a similar, but very different location. The 180Q downpipe terminates in the center of the tunnel. The 225 downpipe terminates on the driver's side. Our systems are accurately designed for each model and cannot be interchanged. Please observe the following guidelines when installing our 3" cat-back:

• If you have our 225 3" downpipe installed - use our 225 3" cat-back
• If you have our 180Q 3" downpipe installed - use our 180Q 3" cat-back
• If you have a custom 3" downpipe installed on a 225 - use our 225 3" cat-back
• If you have a custom 3" downpipe installed on a 180Q - use our 180Q 3" cat-back

TT owners with hybrid turbocharger setups take notice! Each cat-back fits the turbocharger and respective downpipe it was designed to fit. 180Q owners with 225 hardware should use the 225 cat-back or turbo-back. 180FWD owners should steer clear - this cat-back won't fit regardless of turbocharger swaps.

180Q Single Tip vs. 225 Dual Tip

Both our 180Q and 225 3" cat-backs have dual 4" tips. 180Q owners will need to install a 225 or 3.2 rear valance when installing our cat-back. During product development our 180Q test cars insisted on converting to the 225 rear valance. In our research, we found the majority of 180Q owners preferred the dual tip. At this time we have no plans to offer a single tip cat-back for the TT.

Minor Modification Required

Although our 3" cat-back follows the same path as the factory exhaust, it's significantly larger in size and requires minor trimming of the rear muffler heatshield. Roughly 2" x 7" needs to be removed, enlarging an existing opening. Reference the pictures below for exact measurements. Trimming can be performed with basic tin snips without removing the heatshield.

click image to enlarge

Custom Fitments

Although our 3" cat-back was designed to fit our 3" downpipes, it can be installed on other downpipes. Custom 3" downpipes and 3" downpipes built by other manufacturers are equally worthy and equally common. Fitment to these downpipes is not difficult, but requires more than a clamp-on install. Please read our TT 3" Cat-Back FAQ for detailed instructions and alternative fitments.

Motor Mounts Recommended

We highly recommend upgrading your dogbone motor mounts when using our cat-back exhaust system. Worn out factory bushings cause excessive engine movement. Engine movement translates directly into the exhaust system - flex section or not. If your engine is slinging back and forth so is your exhaust. This means rattles, panic, and worry. Our system is designed to be used with motor mounts. The fitment is exact - 3" piping is a lot to stuff under a TT.

Non-Resonated System

We do not offer our TT cat-backs in a non-resonated configuration. Long term testing proved to us that a non-resonated 3" system is simply too loud for the TT. The design of the TT exhaust and body lends itself to high exhaust volume inside the cabin. Without a resonator the sound's not unbearable, but we don't like it. Outside the car the exhaust note loses the refined sound we're after. Inside the car exhaust volume increases, amplified by a test pipe and even worse without the rear seats. For these reasons, we do not offer a non-resonated configuration.

The Sound

Our 3" exhaust emits a suggestive rumble, a refined sound at low rpms, and a powerful tone at high rpms... but can become loud fast. It's important to us that our customers understand what conditions turn up the volume before finding themselves dissatisfied. Please read our TT 3" Cat-Back FAQ to learn more and be sure to watch our video sound clips above!

Power Gains

Power gains have not been exclusively measured for this cat-back system. Power gains related to this system depend entirely on what's in front of it. Typically, this would be our 3" downpipe resulting in a true 3" turbo-back. We've proven the gains achieved using our 3" downpipe, but we haven't done any dyno work to prove gains before and after adding this cat-back to our downpipe, or even a full turbo-back.

Dyno testing of our 225 3" downpipe proved gains of 9.3 hp and 19.3 ft/ lbs at the wheels. Addition of the 3" cat-back adds power throughout the power band - especially in the higher rpms. In our testing, we added the cat-back to our 225 equipped with our 3" downpipe and felt gains equal to the downpipe!

Questions

Last but not least, if you have any questions about our 3" cat-back systems or any of our exhaust systems don't hesitate to contact us. We're available by phone, fax and email to answer any question you may have.

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