I use to have a Magnaflow 94009 cat on my car but replaced it with a bullet muffler. I've decided i want to put the cat on but i'm unsure which side originally went towards the front of the car. Does it matter? or can you put either side toward the front. I was hoping to find a direction arrow on the dang thing but no luck. I had the cat welded on by a shop so i don't know if there was ever a specific side to go toward the engine. Any help would be appreciated.

 

On mine the pipe (looks capped) comes out and runs toward the front of the car on the inside if this helps. I just looked inside it tonight and the front has a screen but i don't know what the back side looks like.

 

I think the "screen" you are seeing is just the internals of the cat. It is just a honeycomb shape that runs all the way through it.

To the OP, I don't think that it really makes a difference. If you have used the cat before, one side will look more burnt than the other (my factory one had more carbon buildup on the motor side).

Think about universal catco cats, they have a heatshield on one side, so depending on which side of the car you use it on, will determine which end is facing front since you want the sheild facing the floorpan. Shouldn't matter.

 

I personally would try to turn the cat around and use it the opposite direction you originally used it if possible. It just might act a bit like blowing air through your air filter to knock out old dust and make your air filter last a bit longer.

 

I only had the cat on for less than a week so i don't think thats an issue. I care more about a long life of operation more than anything.