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other than emission purposes, what are the advantages and disadvantages of cat vs no cat? is there much of a power difference from a high flow cat vs no cat
 

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That is a very good quesiton. i would also like to know the answer to this. but, to add onto your question....

With light mods (ex: CAI, cat back, etc) will a Grand Prix be able to pass emmissions easily with high flow/ no cat???

Hopefulyl, someone will have the ansewr to our questions.
 

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As far as emissions....
In Ohio, We have a visual check for the cat and then they just scan the vehicle. If the car sets an SES light from a high flow cat you could get around it by buying an o2 sim to keep from setting this code. I have heard of some gutting the cat so they can pass the visual while still getting the "benifits?" of not having the cat.
 

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Some parts of Ohio. :D

No cat, you will fail visual and you are screwed. Gutted cat will pass visual and depending on how yoru car is you may pass as well. generally all they do is look to see if you have an SES light and if you are throwing any codes.
 

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jbsplus3 said:
other than emissions........what are the advants and disadvants?
Disadvantage,,,,,,, it may bother you if you're environmentally conscious. LOL

Advantages,,,, MORE FLOW, due to less restriction. I honestly have no idea what kind of HP/theoretical gains you could expect, but if you can get away with beating the guts out of it, go for it. Dont forget your O2 simulator. :rolleyes:
 

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disadvantage, no Cat=DRONE

My exhaust became very droney after removing the cat, and even adding a resonator only helped a little, i think a high-flow cat is the way to go for all around performance and driveability.

Mat
 

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Personally, I just swapped out the stock cat for a 3" CarSound Magnaflow cat,which is supposed to get a little bit better flow than stock, but still be OBDII/emissions compliant. When I 1st had it installed last month, the SES light was going off, but it was intermittant, and I think it might've only occurred when I would drive hard, and push more exhaust past the O2 sensor than the new cat was able to clean up.

I don't know how NY plans on testing emissions, now that the entire state will do E-check, not just the city, so instead of worrying about my SES light chances, I had the code programmed out. ;) The following is how NY plans to do their OBDII inspection:

NYSDMV said:
How will the inspector conduct the new emissions inspection?

The inspector will complete the same low-enhanced emissions inspection that is currently required for the Upstate Area. To conduct the additional test of the OBDII, the inspector will use the OBDII cable to connect the NYVIP equipment to the OBDII diagnostic link connector (DLC) on the vehicle.

A vehicle will fail the OBDII test if:

The DLC on the vehicle is broken or gone.
The OBDII malfunction indicator light (MIL) on the vehicle does not illuminate when the ignition is set to the ON position and the engine is not in operation.
The MIL remains illuminated when the engine is in operation.
The OBDII readiness monitors on the vehicle report that the OBDII system is not ready for the test.
Myonly worry is that this new tool that the DMV is making inspection stations purchase, does more than read for a code, but reads if a code is actually supposed to be triggered. If so, I'll be beat, which is why I hung onto my stock cat.

A sound aspect changes with no cat as well. You will get a more raspy sound with no cat, unless you have a free-flowing system that incorporates enough dampening (resonator/etc.) to overcome the increased amount of frequencies being passed through.
 

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This is off of the ZZP website on how to eliminate kr. It might give you an answer.

"...I believe the biggest restrictions in the factory system are the downpipe and the manifolds. I had the ‘99’s downpipe replaced with 3" tubing with the factory flex left in place. This goes into the factory cat, which is gutted. I want to add here that testing before and after gutting the cat produced results showing that the cat was not a restriction even while running 13.2’s. Even though I don’t think that the factory cat is much of a restriction the mod is free so hey it can’t hurt. Just make sure you have an O2 sim before doing this..."

http://www.zzperformance.com/zzp/info/info_eliminatekr.htm
 
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