I know that you can buy cat back exhausts, headers, and high flow cats but what about the piece of piping that goes from the headers to the cat? What is it called and do they sell them pre-made or do they have to be custom made? I would think that you would want to replace that too for the entire benefit.

 

The header and the cat are directly connected. :wtf:

 

They are?

 

Here's how your exhaust goes.

Header --> Cat --> Catback

The pipe that goes from the header to the catback is the cat.

 

factory exhaust manifolds are usually two piece, that lower piece is the a-pipe

 

If it is stock, you have the exhaust manifold which drops down to in front of the block from there you have the down pipe which curls under the block and connects to your cat via a flex joint usually. After the cat you have your piping whether cat back system or custom exhaust piping running to the rear of the car and the muffler.

If it is aftermarket you may still have a 2-piece header (manifold and down pipe) but most likely a one piece header connected to the cat via a flex joint.

The flex joint is critical, without it your exhaust piping would crack when the motor torques around.

 

By the way if it is the flex joint you are referring to they are like $10 if that at Midas or somewhere like that.

When I put my JDM motor in I got the exhaust manifold which really isn't a manifold on the JDM H22, it's more like a 2 piece header. Anyhow when the motor was yanked from the donor in Japan rather than cutting after the flex joint and sending that with the downpipe, they just cut right through the flex joint very close to the end of the down pipe and the o2 sensor. Because it was so close and there was not much material to work with, Midas charged me like $200 to clean it up and weld on a new flex joint then cut the cat out and move it back to line up with the new flex joint. All in all it was $200 but the actual flex joint was only $10... the rest was for labor because they had to do a lot of cutting, relocating, and welding.