I’m at the point in an engine swap where as the saying goes “mistakes were made” to keep it short I have a 2000 engine in my 98. My question is if I keep the 2000 crossover pipe and modify my exhaust so the pre cat flange will mate with the 2000 crossover will I fail smog? I don’t see why I would but I don’t want to “solve” my problem by making a bigger one.

Any help would be greatly appreciated.

I'd like to believe if the system is sealed end to tailpipe along the way, an 02 sensor is present and the odb2 readings are all "Ready", why shouldn't it pass?

But then again this is government, for the people by the people....Luck.

That was my thought too but as much as I’ve hit my head already on this engine swap I figured it was worth asking the group before I shot myself in the 🦶🏼

There’s a smog shot across the street from the muffler shop I’m going to try to get the flange from so I’ll stop in there and see if they have any thoughts

It's better to transfer over both the exhaust manifolds and the crossover pipe from your old 98 engine to the 'new' 2000 engine. Is that no longer an option? Unfortunately you've learned the hard way that Toyota changed the pipes and didn't really tell anyone, I used to sell used parts and this was a hard one to explain to people.

If you can't swap them over you can weld them. My catalytic converter doesn't even have a flange, it's welded straight to the pipe and it passes smog. Technically, my exhaust is CARB illegal as I had the piping coming out of my headers increased to 2.5" instead of the stock Toyota 2.25" but who's ever going to know that unless I tell them?

Big thing is no leaks. If there's a leak it'll start to throw codes and codes never pass.

Yeah, the original motor is gone with manifolds 🤦🏻*♂️ I bought a used crossover that matches the flange on my cat but after 2 struggle sessions, one to remove the one on the motor and one to attempt to install the “correct” one we realized it wasn’t going to fix the problem. I’m taking the one that bolts to the manifolds that are currently attached to the motor and my cat to an exhaust shop today to see if I can get a flange with a chunk of pile on it that I can use to make happiness under there 🤞🏼

Technically illegal, but make it look stock and it'll be fine. You know, heat shields in place, etc.

-Charlie