Front pipe interchangeability between 01 and 99

Hi Guys,
When I search amazon or the usual parts sites, I see a different front pipe for an 01 vs a 99. Guy at work has one form an 01, I have a 99. I'm going to be needing one before too long and was wondering if they were interchangeable?

Also, has anyone ever rigged up an additional hanger midway between the cat and muffler? That's a lot of unsupported area there and mine always end up bowing down once I have a clamp or two on after tailpipe and muffler replacement. Just wondered, I can't remember ever seeing anyone having done that and it would make sense to help keep the front pipe from smacking off the cross member.

i think the 01 has more emissions stuff if not more cats.

90xj06 said:

i think the 01 has more emissions stuff if not more cats.

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When he described his, it sounded like there were more 02 sensors than mine has. I believe mine only has the one at the top, then it has the one after the cat. Mine does have the smaller (precat?) bump in it though.

im not sure if it will directly bolt up.you may have to plug o2 holes. but the overall length might be different.

90xj06 said:

im not sure if it will directly bolt up.you may have to plug o2 holes. but the overall length might be different.

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Yeah, the pics online all look to be different enough to question it.

I have a 97 which is the same as 99, and an 01 with the mini-cats. The front two pipes are not interchangeable. Engine side: The 01 has a triangular flange with a gasket between it and the mini-cats. It is also parallel to the road. There are no O2 sensor bungs in the 01 pipe, they are all in the mini-cat assembly. The 97-99 type bend upward and have a 2 bolt setup to the exhaust manifold. Back side: The 01 has a gasket flange to the other catalytic converter. The 97-99 is not flanged and is designed for a cat to be welded/clamped into place.

md21722 said:

I have a 97 which is the same as 99, and an 01 with the mini-cats. The front two pipes are not interchangeable. Engine side: The 01 has a triangular flange with a gasket between it and the mini-cats. It is also parallel to the road. There are no O2 sensor bungs in the 01 pipe, they are all in the mini-cat assembly. The 97-99 type bend upward and have a 2 bolt setup to the exhaust manifold. Back side: The 01 has a gasket flange to the other catalytic converter. The 97-99 is not flanged and is designed for a cat to be welded/clamped into place.

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Thanks a lot for the clarification! I really didn't think they were interchangeable, but the guy kept insisting they were they same.