Performance Exhaust Systems
Catless Downpipes
The straight-through variant: same routing, same fixtures, no catalyst section in the pipe.
A catless downpipe is the front section built without a catalyst: a straight-through pipe that follows the same routing, flange faces and sensor positions as the catted variant of the same application. The variant is described the way the workshop builds it — by fitment, construction, material and finish — for the buyers who specify it for their programs.
Sizes run through the 3-inch, 3.5-inch and 4-inch classes, in SS304 and in titanium. The fitment list is the downpipe family's: BMW B48, B58, N55, S55 and S63; Mercedes-AMG applications; MQB cars on EA888 and EA855; McLaren, Mini Cooper, Ford Mustang EcoBoost and Honda Civic 1.5T.
- Straight-throughNo catalyst section
- SS304 & titaniumBoth materials in production
- Same fixturesAs the catted variant
- 3in–4in classesSizes by application
Construction of the Straight-Through Variant
Without a catalyst section to house, the pipe is a single mandrel-bent run from the turbo flange to the mid-pipe joint, TIG welded on the same fixture as the catted version of the application. Flange faces are machined after welding; sensor bosses are placed from the scanned positions of the original part, so the pipe installs against the car's existing hardware points.
Decat is the trade's other word for this variant, and race downpipe is what some listings call it; the part is the same in each case — a straight pipe of a stated diameter, material and finish, for a stated engine.
| Element | Specification | Notes |
|---|---|---|
| Pipe run | Single mandrel-bent run, no catalyst section | Routing follows the OEM part's scan |
| Materials | SS304 or titanium | Titanium carries the burnt-blue finish |
| Joints | Flange at the turbo; V-band where the application uses it | Machined faces |
| Sensor bosses | From scanned OEM positions | Placed before welding, checked on the fixture |
Fitment Notes by Application
The BMW applications are the family's centre of gravity: the B58 page details one engine's version in full, and the EA888 page does the same for the Volkswagen Group cars. Both are built to the same construction — straight pipe, application fixture, scanned boss positions.
For applications outside the standing list, send the engine code. The reply classifies the application as production, adaptable from an adjacent fixture, or development, and quotes accordingly.
Specifying a Catless Order
An order specifies four things: the application, the size class, the material, and the finish — brushed or polished on stainless, burnt blue on titanium, ceramic coating available across the variant. Heat shields are specified where the application lists them. Everything else — flanges, bosses, joints — follows the application fixture and is confirmed in the reply.
Ask about catless downpipes for your vehicle
Send your vehicle, engine and model year. The catless downpipes options that fit are confirmed first, then quoted with finishes and hardware.
Send an Inquiry