Do all 2000 Nissan Altima's have two cats? I gutted my front cat (part of the exhaust manifold) which was plugged and the car runs much better now. After the flex pipe underneath the car there is what appears to be a cat after the flanged connection, but before a resonator. Every replacement picture I see shows the cat for this location as being flanged on both ends and 3-way with a tube coming out the side. What I see is flanged on the front and welded on the rear with no 3-way tube. i'll post some pictures later.

Yes the second cat has flanges on both sides. I took mine out and it was also choked. Well it had pieces of the front cat stuck in it like small pieces of rock.

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