Fact Check: 1ZZ/2ZZ mid pipe compatibility

jden · 2025-10-02T00:29:15-0400

1ZZ and 2ZZ mid pipes can NOT be interchanged. The 2ZZ header flange has a larger ID, gasket, and smaller bolt spacing than the 1ZZ header flange. The 2ZZ muffler flange also has a larger ID, gasket, and bigger bolt spacing than the 1ZZ. To make it work you will need:
-Some wiring on the interior
-Header flange swap OR 2ZZ engine
-Muffler flange swap OR 2ZZ muffler
Oxygen sensor wise, the connectors appear to be the same forward and aft on the 2zz mid pipe, and same on the 1zz mid pipe and the 2zz mid pipe. 1zz forward O2 sensor is on the engine harness so I haven’t checked that. My informational contribution for today. I was gonna try run this on my 1zz but it’ll have to wait until I’m 2zz

Esso · 2025-10-02T14:09:55-0400

Hey, thanks for sharing. I was going to consider the 2zz exhaust as well. But will need to mod based on your finding.

Might go Magnaflow at some point or custom on 1zz.

75aces · 2025-10-02T14:58:31-0400

Technically speaking, you can cut off the flange and weld it into the matrix/corolla exhaust. Though it’s a moot point in way of time.

Personally, go PPE midpipe from MWR and upsize the remainder based on the end of the flange from the PPE. I like free flow of same diameter.

My downpipe on the Mazda is 3” and rest of exhaust is 2.5”. I’ll get that remedied when I’m back on the road.

jden · 2025-10-08T00:57:25-0400

My goal was two things, future prep this car for 2zz swap once i can find a motor (i have trans, ecu, axles, harness, mounts, everything but a running motor) and to clear my P0420. I ended up purchasing a minicatalizador for that. The dream setup is Skunk2 alpha 06-11 civic si header, 2zz header flange, full 3" with a vibrant resonator and varex muffler. but i have a lot of dreams, the 2zz swap has been one for about 5 years now. so has that exhaust setup.

Fact Check: 1ZZ/2ZZ mid pipe compatibility

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