I changed the headers and down-pipe on my 06 OZ leaving a gap between my mid and down-pipe where the old cat was. Im going in tomorrow to fill this gap but do you guys think i should put another cat in or just straight pipe it? Ive heard straight pipe is more horsepower but ive also heard that cats save you a lot of gas mileage

Anyone know the difference in mileage with or without a cat?
What do you guys think i should do?
thanks!

 

If you can find a highflow cat. They work great and no problems with police

 

I've got the best mpg's I've had with my high flow cat. Did you ever end up deciding?

 

the cat really dont matter, its what the o2sensor reads to mix the air/fuel ratio. but a high flow cat would be better, you cant mess with these newer cars exhaust too much like you can on the older cars since its all about computers now days

 

don't straight pipe it xD just do what everyone else says and go with high flow cats. If you straight pipe it you will get very annoyed with it fast.

 

Well, it depends on what header/exhaust manifold you run. Pretty sure the 2006 model had the "cat in the header and cat in the midpipe", which I'd consider overkill.

I was perfectly happy with a gutted header and a high-flow cat, but you could also get the straight pipe and leave the header cat stock.

To each, his own.

 

It really depends on how you're set-up is right now. While freeing up the flow of your exhaust is ideal, there's a threshold in terms of backpressure where too little can do damage to your horsepower.

Think of a garden hose with water, where the Cat converter would be like a nozzle or a kink in the line, there's a lot of pressure and not as much flow. Take out the kink or nozzle and now you're pretty much free flowing. Now take the same amount of water and use a fire hose instead, which is pretty much whats gonna happen with an upgraded exhaust running a straight-pipe.

Even for me, a high-flow caused me to lose power in the low-end of the power band. Unless you performed heavy intake mods, ported your head, and all that jazz, freeing up your exhaust with headers, a high flow cat, and an aftermarket exhaust would push that backpressure threshhold... Different story if you're turbo'd though =P

 

Go with the High Flow CAT, Saves problem with the police and the harrassing engine codes your car could throw up when it detects the out of limits emissions you might give off