Exhaust
#11
02-13-2012, 08:37 AM
Downpipe != catalytic converter.
Your stock exhaust goes turbo ->cat ->downpipe ->rest of exhaust. People often replace the cat with what's known as a "test pipe" to increase exhaust gas flow and low end torque. That's what will cause you to fail emissions, because it replaces your cat with a ~2' piece of pipe. Some test pipes will trigger a CEL for a cat efficiency code, but this can be prevented by using a spacer for the secondary O2 sensor. If your state uses exhaust sniffers or does a visual inspection, this will also cause you to fail emissions, yes.
The downpipe is separate from everything I covered so far in this post. It bolts to the rear flange on the cat/test pipe and connects to the rest of the exhaust system with a large sleeve clamp. It's usually referred to separately from the test pipe and the rest of the exhaust because it can be removed by itself and many aftermarket exhausts don't come with a new one.
Your stock exhaust goes turbo ->cat ->downpipe ->rest of exhaust. People often replace the cat with what's known as a "test pipe" to increase exhaust gas flow and low end torque. That's what will cause you to fail emissions, because it replaces your cat with a ~2' piece of pipe. Some test pipes will trigger a CEL for a cat efficiency code, but this can be prevented by using a spacer for the secondary O2 sensor. If your state uses exhaust sniffers or does a visual inspection, this will also cause you to fail emissions, yes.
The downpipe is separate from everything I covered so far in this post. It bolts to the rear flange on the cat/test pipe and connects to the rest of the exhaust system with a large sleeve clamp. It's usually referred to separately from the test pipe and the rest of the exhaust because it can be removed by itself and many aftermarket exhausts don't come with a new one.
#16
02-16-2012, 12:40 AM
Man I met a guy up today that was selling a magnaflow universal muffler ( part#14816), I did not expect it to be that huge! I ended up not buying it from him due to the tips being so big. I'm used to seeing nice fit ones on audi's maybe it would look nicer while on the car? The inlet is 2.5 and the outlet is 3.5. I'm assuming the outlet is the tips?
#19
02-16-2012, 09:03 AM
Done refers to the resonance people sometimes hear from their exhaust when driving at part throttle and/or highway speeds. Most well planned exhaust setups (including straight pipes in some cases) sound pretty good at WOT because all you can hear is the engine, but there can be lots of loud resonance at part throttle, which makes them impractical for a daily driver. Its tough to find a good sound/video clip of resonance because the microphones on cheap cameras and cellphones have a hard time picking it up.