I bought my N/A s4 back in September. Some stuff was already done to it. One of the things that was done was the air pump was removed and the previous owner installed straight pipes and pulled the cats. The car is very loud now. I was thinking about putting in high flow cats for smog reasons. Will the air pump be necessary to re-install any cats?

 

bump

 

Nah, you s/b able to find a cat that doesn't need extra air.

I think you need backpressure to open your 6th ports though. Is that pipe still intact?

 

Rotarys run alot hotter than a piston engine. Honestly I believe you should put that air pump back on, if the heat isn't an issue at first, it will greatly shorten the life of the cat down the road without the pump.

 

Thumbs up, that's what I was thinking too.

You can try to rig an extra vaccum line off the manifold somewhere for it... someone else will know I'm sure.

--Gary

 

I don't think it has anything to do with heat, but I could be wrong. The ACV only sends air back there under certain conditions.