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Discussion Starter #1
I have a stock exhaust system and planned on only adding a Megan midpipe.

If I also add secondary cat deletes would I gain any power above and beyond just the Megan?

What will happen to noise levels above and beyond the Megan?

Am I likely to still pass a tailpipe sniffer emissions test since I will indeed have my primaries still in place?

Thanks.
 

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We've tested this on the dyno few times with our demo car.

Deleting 2ndary cat does not do much since o2 sensors are not working properly or not functional.
Sure you can still make the bungs and use defoulers to avoid the check engine lights (still pass emissions without problems) but Lambda motor and ECU works on all combination of things like I told you on the phone last time.

It really needs monitor proper water temp and Cat temp in order to perform the set A/F ratio.
We do not change any of A/F ratio when it's cold start and everything is warmed up good to go.
That also means if o2 sensors are not sensing properly, ECU will not be reading right still thinking it's still at cold start.
For our demo car adding stock cat back on added about 12rwhp compared to straight pipes.
Also if you look at the stock cats, they are very well made almost like aftermarket highflow cats.
 

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We've tested this on the dyno few times with our demo car.

Deleting 2ndary cat does not do much since o2 sensors are not working properly or not functional.
Sure you can still make the bungs and use defoulers to avoid the check engine lights (still pass emissions without problems) but Lambda motor and ECU works on all combination of things like I told you on the phone last time.

It really needs monitor proper water temp and Cat temp in order to perform the set A/F ratio.
We do not change any of A/F ratio when it's cold start and everything is warmed up good to go.
That also means if o2 sensors are not sensing properly, ECU will not be reading right still thinking it's still at cold start.
For our demo car adding stock cat back on added about 12rwhp compared to straight pipes.
Also if you look at the stock cats, they are very well made almost like aftermarket highflow cats.
You will not get a CEL from removing the secondary cats. They do not contain O2 sensors. Just removing them alone without any other changes to the system will result in that famous 3.8 rasp. You will need to either get the megan midpipe, or have one custom made to get rid of this. As for additional power, i do not recall if anyone has ever dyno'd the car after just removing the secondary cats.
 

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Nawesome.
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You will need to either get the megan midpipe, or have one custom made to get rid of this. As for additional power, i do not recall if anyone has ever dyno'd the car after just removing the secondary cats.
Even with the megan mid-pipe, the rasp of baffle rattle will remain with the stock muffler (drove me nuts so I ended up putting the cats back in).
 

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Even with the megan mid-pipe, the rasp of baffle rattle will remain with the stock muffler (drove me nuts so I ended up putting the cats back in).
True, I totally forgot that I had changed out my stock muffler for a magnaflow before I did the y pipe.
 

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Noise. No power. No good.
 

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The OG
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I'm probably gonna be putting mine back in come this summer.
 

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Discussion Starter #8
Good info guys, thanks.
 

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Well, Deleting the 2nd cats and going straight pipe with 2 22in resonators for $200 IS THE BEST MOD I have done. My butt dyno and rear tires agree.:cool:

EDIT: You cannot leave the stock, or any axleback in or you will have sound issues. cooler
 

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I made some for my car. I already had a magnaflow catback. With the cat-deletes, it really opened up the sound I was looking for. There is a touch of drone under 1500rpms. I don't know whether I could say I felt a difference or not. I have made a few sets for members on here who have all had positive experiences. I still have the stock primary cats, and if I get headers, I will probably put some high flow cats on there.

There are no o2 sensors monitoring these, so you won't mess up your tune, or have cel issues.
 

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^+1 on socks, he made me a set and in combination with my ark catback it sounds amazing, although i have heard that if you don't have an aftermarket catback it sounds very raspy.

As far as power is concerned i don't really have access to or money for dyno time so i can't help with any numbers on that.
 
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