General Exhaust questions

[g8gxp]

Ok, so i'm still a little confused regarding aftermarket exhausts.

Under what situation would you experience cabin drone?

A full LT header system will elminate drone? or is it still dependent on finding an appropriate muffler?

In FL we don't have emissions testing so in theory i could go catless. Is there a huge performance difference between catless and high-flow cats? what are the pros and cons of going catless?

Thanks,

[GRRRR8]

Drone is almost always created by the muffler. I have ARH LTs with factory muffs. 0 drone.

[-Ray-]

Ok, so i'm still a little confused regarding aftermarket exhausts.

Under what situation would you experience cabin drone?

A full LT header system will elminate drone? or is it still dependent on finding an appropriate muffler?

In FL we don't have emissions testing so in theory i could go catless. Is there a huge performance difference between catless and high-flow cats? what are the pros and cons of going catless?

Thanks,

There isn't going to be much performance difference weather you are cat less or high flow cats. The major difference is pollution.
The headers by themselves do not contribute to drone. That's harmonics caused by the muffler.
My Magnaflow has a significant amount of drone at cruise. It can be tuned out with the radio with no problem.
I'm going to be working on creating an axle back with minimum drone.

[G8Smitty]

I removed drone by shutting off AFM. I couldn't be happier.:)

[Art708]

I removed drone by shutting off AFM. I couldn't be happier.:)

How does one shut off AFM? And how much difference did it make in gas mileage?

[SRG963]

Has anyone made high flow cats for the G8 yet?

[Chewy]

Has anyone made high flow cats for the G8 yet?

I just emailed M/F with that exact ??

Will let ya'll know.

[SRG963]

I just emailed M/F with that exact ??

Will let ya'll know.

Sweet :pee:

[-Ray-]

How does one shut off AFM? And how much difference did it make in gas mileage?

Most tuners can turn it off.

[G8Smitty]

How does one shut off AFM? And how much difference did it make in gas mileage?

If you have HPTuners software it has the option to disable it. Or, if you have your car tuned, you can ask the tuner to do it, which is what I did.

I have noticed an increase in overall mpg since I had it shut off. To be fair, I do not do much highway driving and the tune should have netted me a little extra as well.

My AFM would toggle on and off a bunch on my normal day-to-day driving. IMO it affected performance adversely. I also do not like the sound at all through the axlebacks I have (I still have the bullet resonators).

I’m surprised that the AFM is not a bigger issue with more people.

Even though the parts are supposed to be better in the L76, I would have rather have the LS2 over the L76 in my G8. Although, I think my tuned G8 would give my old stock LS2 GTO a run for its money.

[G8GTlawride]

Drone is almost always created by the muffler. I have ARH LTs with factory muffs. 0 drone.

What he said. Except, "Quiet"

[djchubbs]

i have just over 6k on my car and have noticed the drone with stock exhaust

[GRRRR8]

i have just over 6k on my car and have noticed the drone with stock exhaust

???? You may hear DOD when active, but you cant have a drone, or you are the 1st!

[Art708]

I don't know how there could be any drone with the stock muffs. Man, those things are as big as shitcans. But the factory exhaust must be pretty well dialed in from the factory. I was really surprised that the expensive Magnaflow catbacks didn't do anything for me in the power department......just more noise. I'm wondering whether extending the exhaust tips a bit farther out from the car would decrease the droning. My wife gave me a month before I went back to the stock system. I'm keeping it handy just in case. Or maybe use the Magnaflow system some other mufflers????

[Chewy]

I don't know how there could be any drone with the stock muffs. Man, those things are as big as shitcans. But the factory exhaust must be pretty well dialed in from the factory. I was really surprised that the expensive Magnaflow catbacks didn't do anything for me in the power department......just more noise. I'm wondering whether extending the exhaust tips a bit farther out from the car would decrease the droning. My wife gave me a month before I went back to the stock system. I'm keeping it handy just in case. Or maybe use the Magnaflow system some other mufflers????

They have a street system now with a resonator/muffler before the rear two to reduce more drone. Maybe look into adding it to yours???

[G8V8]

Testing with LTH and pipes back to the stock axle-backs showed only a 2 HP gain with no mufflers vs the stock axlebacks. The stock mufflers are big, quiet and heavy but flow well. The 2 resonators upstream in the stock catback have smaller diameter tubing than the rest of the stock catback.

[jbradsh1]

I wonder what eliminating the resonators in the stock cat back and replacing them with an X pipe would do for performance? Or Sound?

[GXPaycheck]

I wonder what eliminating the resonators in the stock cat back and replacing them with an X pipe would do for performance? Or Sound?

I don't know about performance, but as for sound there's not much difference. I put my stock muffs back on just for the heck of it. Now I have cats to H-pipe to muffs. Slight sound difference, drone the same as stock.

[G8V8]

I don't know about performance, but as for sound there's not much difference. I put my stock muffs back on just for the heck of it. Now I have cats to H-pipe to muffs. Slight sound difference, drone the same as stock.

So replacing the twin muffler and 2 resonators with an H-pipe didn't increase the drone from stock? I've never noticed any stock drone to begin with. Those resonators are something like 2" pipes and are probably the bigest restriction in the OEM catback.

[GXPaycheck]

My bad, forgot about the bullet resonators. We only removed the large single resonator to make way for the H-pipe. Stock drone is felt more than heard.