[Robbs1le]

I ordered kooks headers and got both off road connection pipes and high flow cats in not sure which ones to use. What's everyone's opinion? I'm keeping the npp exhaust

[rhubar]

I'm wondering the same thing. I just put my order in for some kooks /no cats. I'm gonna try that route but I plan on changing out the rest of the factory exhaust too.

[VAZL1]

I've had both and prefer the cats, not a fan of the exhaust smell without them. The performance difference isn't great enough to justify the pain is causes if you're in a state that test as well.

[jasonz28camaro]

performance wise its only a few HP so its up to you whether you want to smell like gas or not and how loud you want it.

[1967RS327]

Not sure if they have 02 sensors downstream of cats but if they do and you run no cats it will throw a code unless you have it tuned and delete that sensor

[ForgedReality]

Headers, no cats, no mufflers.

[ForgedReality]

Originally Posted by 1967RS327

Not sure if they have 02 sensors downstream of cats but if they do and you run no cats it will throw a code unless you have it tuned and delete that sensor

Not true. Google spark plug defouler exhaust trick. I've done this on my untuned straight pipe, long-tube SS.

[ForgedReality]

Originally Posted by VAZL1

I've had both and prefer the cats, not a fan of the exhaust smell without them. The performance difference isn't great enough to justify the pain is causes if you're in a state that test as well.

There are still places that test? I thought it was federally that any car made after 2008 didn't have to do emissions ever...

[Robbs1le]

I installed the kooks with no cats the decibel of the exhaust is fine with the npp but it is raspy like a mustang. I don't like it. I have the kooks high flow cats that I ordered at the same time and read a bunch of people having issues with cats and forced induction cats so I decided to go with out them. But the noise is making me want to put them on. I just don't want to put the cats on and in 6 months be taking them back off.

[Can'tHave2MuchHP]

You'll melt cats if you modify the car. I used to be a believer in high flow cats for taming the rasp but I've had 3 friends with ZL1s/ZR1s melt cats and pretty much ruin $2,000+ in exhaust systems. The sound cut is not drastic anyways, and the smell for me doesn't exist unless the car is running rich as hell.

[Robbs1le]

Ya that's my dear cause I plan on taking it to 700-750 hp. I guess I'll learn to love the rasp

[VAZL1]

Originally Posted by ForgedReality

There are still places that test? I thought it was federally that any car made after 2008 didn't have to do emissions ever...

Every two years in VA.

[Infern0]

They aren't testing emissions in VA for late production cars, just ODB codes and visual safety requirements (working blinkers, etc) - which DOES include a visual inspection for cats. If one were to say, have high flow cat bodies installed, that were hollow, they would pass that visual inspection. Hypothetically of course.

I wouldn't say the rasp, of the 5th gen anyway, in the above scenario was very noticeable in my opinion. And yes they were hollow because they melted. Luckily I had already done a muffler delete so it all just came out the back. They won't tailgate me anymore.

[VAZL1]

Originally Posted by Infern0

They aren't testing emissions in VA for late production cars, just ODB codes and visual safety requirements (working blinkers, etc) - which DOES include a visual inspection for cats. If one were to say, have high flow cat bodies installed, that were hollow, they would pass that visual inspection. Hypothetically of course.

I wouldn't say the rasp, of the 5th gen anyway, in the above scenario was very noticeable in my opinion. And yes they were hollow because they melted. Luckily I had already done a muffler delete so it all just came out the back. They won't tailgate me anymore.

That is correct you could run dummy CATs, still not worth it in my opinion.