Down Pipe

[AStrikeEagleL15]

Will it hurt your car if you have a cat eliminating down pipe. I was under the impression that not having a catalyctic converter would be bad for the car down the road. That just what I heard though.

[Caplax40]

Down pipes usually just eliminate what's called the "pre-cat" and doesn't eliminate the actual catalytic converter. It won't hurt anything at all.

A pipe called a test pipe will actually eliminate the catalytic converter. The test pipe is just a pipe with no filters or anything inside. This gives good power gains but now your car has virtually no emissions control. You will fail emissions testing, both visual and the sniff test.

I have what's called a hi-flow cat on my Turbo Supra. It's a CC but just allows more flow (duh). I passed my emissions test with flying colors.

[nametakennow]

Ack!

Caplax, got it wrong there. The header eliminates the precat, at least in the case of a B15 Sentra. Some midpipes, such as the DC Sports, delete the actual cat as well.

Eliminating either (or both) cats will never cause you problems except with emissions, as you'll need an O2 sim for your secondary sensor.

[RED_DET]

My question is the downpipe from a NA header or we talking about a downpipe for turbo applications.

[nametakennow]

His car is NA, judging by his other threads. Hence my reference to a midpipe for clarity.