hey guys

Ive had my car now for nearly 5 weeks.

I have doen my paint work to it, tint and changed the rear mufflers.

I put Mahaflows in and I really like them.

Q: I found that I got an instent MPG gain!!! Anyone else experience this??

Also, I have discovered why they may have put those stupid big a$$ things there in the first place. When im cruising I can hear the DOD/AFM kick in very obviously. Its like it rumbles then drops down a note and the drone and vibration kick in depending on speed.!!!???

Im hoping with the VMS tune and CAI (coming), this may be muted somewhat!!??

Also, is anyone getting a bad seal on their window moldings??

Thanks guys

hey guys

Ive had my car now for nearly 5 weeks.

I have doen my paint work to it, tint and changed the rear mufflers.

I put Mahaflows in and I really like them.

Q: I found that I got an instent MPG gain!!! Anyone else experience this??

Also, I have discovered why they may have put those stupid big a$$ things there in the first place. When im cruising I can hear the DOD/AFM kick in very obviously. Its like it rumbles then drops down a note and the drone and vibration kick in depending on speed.!!!???

Im hoping with the VMS tune and CAI (coming), this may be muted somewhat!!??

Also, is anyone getting a bad seal on their window moldings??

Thanks guys

Ditch the resonator in favor of an H-pipe or X-pipe and you will drastically lessen its effect.



S.F.

Ditch the resonator in favor of an H-pipe or X-pipe and you will drastically lessen its effect.



S.F.

I have seen you post this a couple of times.
I am really curious - why does 'ditching the resonators'
result in LESS resonance???

Seems counter-intuitive, to me . . .
And ( as I posted elsewhere ) the opposite of my experience
with a 6.0L V8.

Thanks,
- Ray
In need of a little education –
Not an exhaust system expert . . .

Probably has something to do with letting the left and right cylinder banks' exhaust gasses mix and even out the exhaust tone/note.

Course, Stolen Fox or one of his customers would know more. :angel:

I have seen you post this a couple of times.
I am really curious - why does 'ditching the resonators'
result in LESS resonance???

Seems counter-intuitive, to me . . .
And ( as I posted elsewhere ) the opposite of my experience
with a 6.0L V8.

Thanks,
- Ray
In need of a little education –
Not an exhaust system expert . . .

Ray,

I'm no accoustical engineer so I can only speak based on my GTO experience. Every single one of the over 450 GTO owners that responded who replaced their resonator with an H-pipe or X-pipe reported a decrease in interior resonance and sound volume! You read that right - a decrease in interior resonance. The resonator is in effect a hollow chamber filled with a small amount a packing (see this thread for the insides of the resonator = http://ls1gto.com/forums/showthread.php?t=114481&highlight=resonator+final+report) that allows sound waves to bounce around inside the case. This unorganized slug of sound waves resonates inside the hollow space of the resonator and permiates into the cabin of the vehicle.

The resonance creates the illusion of louder exhaust than is really present on the car. By eliminating resonator and replacing with a synchronizing crossover such as an H-pipe or X-pipe you end up with a much more organized and smooth progression of exhaust pulses through the system. The result is a smoother exhaust note with a nice muscular sound and less interior resonance.

Resonance and drone can be drastically affected by muffler choice. Chambered mufflers (IE: Flowmaster, Spintech, Mac Flowpath) are much more prone to droning.

I'm no engineer so I cant melt everyone's brains with the science behind why it works. I just know that it does because so many GTO owners have reported the reduction in interior drone and volume.

G8 owners "gbcop" and "dodson914" can substantiate as well. They are both running magnaflow axlebacks and H-pipes of my design.

There is a reason why all the major exhaust manufacturers use either an H-pipe or x-pipe instead of dual in/dual out resonators...

S.F.

I didn't hear much of any drone on the way to have the H Pipe installed and I have very sensitive hearing. Now, it could become more pronounced after the mufflers break in a bit more. The H Pipe definitely changed the note of the exhaust, but in a good way. You can hear the exhaust in the car through some of the lower rpm's. But, it's the exhaust NOT drone.

Ausstar, good thread. SF, when will your product be ready?

Ray,

I'm no accoustical engineer
......
There is a reason why all the major exhaust manufacturers use either an H-pipe or x-pipe instead of dual in/dual out resonators...

S.F.

Thanks for taking the time to respond.
I would think that ( for a MFR ) the H pipe would
be cheaper than the “dual in/dual out resonators” . . .
Too bad the 'aftermarket' H install requires welding . . .

And I believe you – just seems v. odd.
- Ray
Axle-back on the top of the Mod List – followed closely by H pipe

Thanks guys...

If you read some of my previous posts you'll see that my plan was always to do the x/h pipe with the rear muff swap because I do know about the res and drone effect. My thing is the pronounced effect of the dod kicking in that is very noticable and especially on freeway trips annoying with or without the crossover. My q is, with an H or X will the noticable sound difference be lessened or still apparent with a crossover???

Thanks guys and thanks S.F for all the help.

Cheers

C

Also, is anyone getting a bad seal on their window moldings??
What exactly are you experiencing?

Thanks guys...

If you read some of my previous posts you'll see that my plan was always to do the x/h pipe with the rear muff swap because I do know about the res and drone effect. My thing is the pronounced effect of the dod kicking in that is very noticable and especially on freeway trips annoying with or without the crossover. My q is, with an H or X will the noticable sound difference be lessened or still apparent with a crossover???

Thanks guys and thanks S.F for all the help.

Cheers

C

It is my belief that given the tendancies of an exhaust system equipped with an H-pipe or x-pipe to have much less vibration and resonance that a straight pipe system. Less vibration and resonance should help quell the odd frequencies created by DOD's operation.

We will all be learning about this together....

S.F.