Help: how to reduce drone with my exhaust (RPI GTM)

[avex8]

Hey guys, i am currently running RPI GTM full system. I love the sound and the power but I HATE the in cabin drone/resonate especially that deep bassy drone, makes my ear almost go deaf. The drone only occur between 2K~3K rpm and there is little drone on the highway.

So now i am thinking about keeping the rpi axle back muffler, switch back to OEM x-pipe, and get turner test pipe (primary cat deleted to gain power). Anyone have this set up? how is the sound and drone noise? would this help reduce the drone and in cabin resonate?

Also what cause the drone and in cabin resonate? going catless or x-pipe or no resonators?

[JOM3JO]

thats why i still have OEM system

[nineonenine]

I've got the UUC Corsa axle back and literally experience NO drone what so ever.

[Krozi]

Originally Posted by JOM3JO

thats why i still have OEM system

Remove yourself from this thread immediately.



OP, you might be able to reduce some drone by hacking up the OEM exhaust and replacing the front pipes with the first set of cats from the OEM exhaust.

[FVM3]

i never care about drone.....the best way you go is back to oem

[geneatals]

RPI makes silencer's (decreases the int and ext sound with a slight reduction in hp from what I remember) for their e60 m and non m systems, wonder if they can offer the same for their e9x m system....might be worth a call to rpi...

[e92Mjunky]

i have heard x-pipe only with factory exhaust..sounds good and has a few hp gains..

[Straight Dave]

x pipes do not create drone

[Grail05]

put a resonator... that should lower it down... depends if yours going to put 4 or 2...the more resonator the the better in your case.... thats up to you.... also putting resonator will keep the noise a bit down inside the cabin but still keep the power that you want.

also you can put a 200 cel cat on the primary side and have a resonator on the back end. to keep the noise down a bit.

if you put the 200 cell cat and the resonator by the cat (like the oem xpipe with turner it will drone more than having the 200 cel cat on the primary...


this is just my experience with my AKRA slip on exhaust.. Akra ehxaust holds the noise and drone... not sure with your exhaust set up... they all depend on your axle back exhaust as well.

[EuroTrip]

I think if it in very simple terms when it comes to drone.

The lower the price, the higher the drone.

[kitw]

^ except you'd be completely wrong.

The RPI GTM system is loud. Going stock midsection + TTP is a good option but it won't eliminate it completely. The Innotech is probably the best in this regard, even with the catless x pipe, closed, it's very quiet and drone free.

There is only so much you can do with the x pipe, if you still want power.

[avex8]

how to reduce he low frequency resonance? The in cabin resonance bug me the most

[Malek@MRF]

Originally Posted by Sean05

put a resonator... that should lower it down... depends if yours going to put 4 or 2...the more resonator the the better in your case.... thats up to you.... also putting resonator will keep the noise a bit down inside the cabin but still keep the power that you want.

also you can put a 200 cel cat on the primary side and have a resonator on the back end. to keep the noise down a bit. .

1) Resonators do not reduce or remove drone, they are used to tune exhaust note frequency.

2) Catalysts do not remove drone, they simply muffle the overall sound because of restriction. This restriction also results in less rasp.

3) More resonators=more weight, more heat, and less power (slightly).

[Malek@MRF]

Originally Posted by jakerx8

how to reduce he low frequency resonance? The in cabin resonance bug me the most

This is not possible with resonators. Resonators are nothing but small bodied straight through mufflers. They will simply control some unwanted overtones in the sound, as long as the designer of the system knows how to implement it.

Cabin resonance is a result of piping design, muffler design and in some cases, both.

[Grail05]

^ just my experience bro... all sounds different with different exhaust.... I had swap couple xpipe with or without resonator the noted above is what i experience... weather resonators does or not add drone it did to my old set up...

But maybe having an AKRA SLIP ON probably gave it that results

[Malek@MRF]

Originally Posted by Sean05

^ just my experience bro... all sounds different with different exhaust.... I had swap couple xpipe with or without resonator the noted above is what i experience... weather resonators does or not add drone it did to my old set up...

But maybe having an AKRA SLIP ON probably gave it that results

An Akrapovic rear section is very silent and well designed, thats where most of your sound and resonance control is being done, not through a couple resonators.

[avex8]

Originally Posted by Malekreza11

An Akrapovic rear section is very silent and well designed, thats where most of your sound and resonance control is being done, not through a couple resonators.

i see... what if i put the oem cat and x -pipe back and just keep the axle back. Would that be a lot quieter?

[Malek@MRF]

Originally Posted by jakerx8

i see... what if i put the oem cat and x -pipe back and just keep the axle back. Would that be a lot quieter?

Yes, it would be far quieter because the factory midsection utilizes 4 catalysts and 2 resonators and a merge balance tube what many refer to as an X-pipe.

[avex8]

Originally Posted by Malekreza11

Yes, it would be far quieter because the factory midsection utilizes 4 catalysts and 2 resonators and a merge balance tube what many refer to as an X-pipe.

I got your point. But i really want to have the primary cat deleted, so i can get most power out of the car. But i don't know if it will help reduce the in cabin resonance by having the tuner test pipe and keep the oem x-pipe (2 cat and 2 resonators).

[Malek@MRF]

Originally Posted by jakerx8

I got your point. But i really want to have the primary cat deleted, so i can get most power out of the car. But i don't know if it will help reduce the in cabin resonance by having the tuner test pipe and keep the oem x-pipe (2 cat and 2 resonators).

The OEM midsection is actually VERY loud with the primaries deleted mainly because of the reason that the merge between the two tubes is very small.

We have cut the stock system apart to see where its short comings are.

The merge section is very small, and the larger the merge the tighter the sound.

[Grail05]

Originally Posted by Malekreza11

An Akrapovic rear section is very silent and well designed, thats where most of your sound and resonance control is being done, not through a couple resonators.

question to you now though is WHY

setup one
1. xpipe with 200 cel secondary cat with resonator

setup two
2. xpipe with 200 cel primary cat with resonator

now why is set up one is louder than set up 2 also setup one drones more than setup 2...

also heres is what i have before as well

setup one
1. x pipe with no cat and res...

setup two
2. xpipe with 4 resonator no cats

now why is my exhaust drones more on setup one than 2 if you say that resonator doesnt reduce any drone or remove drone?

just curious cause it did to my set up...

in the end i decided to have a 200 primary cat with rear section resonator to avoid the drone which is a perfect match for the AKRA...

IM GUESSING IF THAT IS IT BECAUSE OF THE AKRA EXHAUST?

this is just my own experience having 3 different xpipe i had used.

[Malek@MRF]

Originally Posted by Sean05

question to you now though is WHY

setup one
1. xpipe with 200 cel secondary cat with resonator

setup two
2. xpipe with 200 cel primary cat with resonator

now why is set up one is louder than set up 2 also setup one drones more than setup 2...

also heres is what i have before as well

setup one
1. x pipe with no cat and res...

setup two
2. xpipe with 4 resonator no cats

now why is my exhaust drones more on setup one than 2 if you say that resonator doesnt reduce any drone or remove drone?

just curious cause it did to my set up...

in the end i decided to have a 200 primary cat with rear section resonator to avoid the drone which is a perfect match for the AKRA...

IM GUESSING IF THAT IS IT BECAUSE OF THE AKRA EXHAUST?

this is just my own experience having 3 different xpipe i had used.

The answer to all these questions is rather simple actually, restriction. The point of the "x-pipe" is to add power and reduce weight substantially, surely its not for cosmetics because its not a visible item.

Adding all those extra components in the system is creating restriction (especially the catalysts), creating additional heat and adding substantial amount of weight. I would like to reiterate that the purpose of a mid-section is to add power as much as possible.

The best way to test your theory is to put straight through piping as your rear section, and then messing with the multiple mid-section setups as this will provide an escape for the exhaust gasses and pressure wave through a controlled tube rather than just letting it dump out right after the midsection. Eliminate the variable, which would be the behavior of the rear section and make it straight through, muffler-less, tubing exiting the rear bumper.

High end exhaust systems are, well, systems because they are designed to work together systematically. There are some well thought out, well crafted systems out there, as well as some terrible ones.

The Akrapovic is a good system, hence the price and popularity.