If I gut the cat will the back pressure still open up the ports?
 

Just wondering, I was also wondering since I have a S4 if I can get rid of the air pump and get the block off plates since my cat opens the ports. Thanks

If you gut the main cat, in most cases there won't be sufficent pressure to open the Aux Ports, as well as be breaking several federal and in many cases state laws.

If you remove the cat or the guts of the cat you could remove the air pump and block off the ACV, but the car will probably backfire on lift throttle situations.

I dont mean to high jack his thread but will those ports still open with a high flow catalytic converter?

I have a Bonez Superflo and the ports do open. Prior to that I had a gutted cat. My ports did open with it. You might have problems if you are running a large diameter (above 2 1/2") exhaust, freer flowing mufflers, etc. Not sure about, though.

I have an s4 with presilencer and downpipe and the ports open fine.. why gut the cats thou.. they are expensive.. just get a pipe..

The pre-silencer is normally required for the aux ports to work, if the rest of the exhaust is too free flowing.

I dont have a presilencer I just have a header and a race pipe, thats why instead of putting in the race pipe I would gut the cat so my ports will still open

perhaps you still have the stock catback???

yeah the stock cat back is still on, with a big hole in the cat

pretty common to have the stock cat back still have enough pressure, to activate the aux ports, but when you go to a more free flowing design with no cats you probably won't have enough back pressure.