gudmundur

I have a Vibrant resonator which I would like to install to try to minimize drone form my Invidia exhaust.

But my local exhaust shop sayst that the best thing would be to replace my cat with the resonator but that they need the flanges on both sides
I think that the 2 bolt flange which bolts to the header is easy to get, but the 3 bolt one that bolts to the cat-back seems to be hard to find.

Does anyone know if these flanges can be bought somewhere ?

Gernby

The local exhaust guy is totally incorrect. There is no worse idea than to put a resonator where the OEM cat is! The location of the OEM cat is actually the biggest reason why the S2000 has such low midrange torque! Putting the "king daddy of all resonators" in that same location would be HORRIBLE! (I'm not guessing ... I've tested it) I don't believe drone would be any better either, since the pipe lengths would be all wrong for drone reduction.

The best (money is no object) fix is to replace your OEM cat with one of my mid-pipes. Drone goes virtually to zero (definitely zero to the human ear), and you remain 49 state legal while also getting a very significant gain in performance. The cheapest fix is to replace the OEM cat with a straight test pipe, but this is illegal and will make the exahust very raspy. If you combined that with the Ultra quiet resonator in place of the small bottle resonator, the rasp issue would go away.

Gernby

If you really want to keep your OEM cat, then another good option would be to swap out the bottle resonator with the Ultra Quiet resonator, then install a closed-ended branch duct (similar to the OEM "weiner pipe") right in the middle between the OEM cat and Ultra Quiet resonator. It would need to be exactly in the middle and equal to 1/4 the distance between the expansion openings. (measure from the convergent cone of the OEM cat to the first perferations inside the Ultra Quiet resonator)

Gernby

I should mention that I assumed you have the Invidia Q300 dual. Now that I look back, I see that you didn't mention which model you have. Most of what I said above is specific to the Q300.

Weasel497

Quality information right there. Would it be safe to assume roughly the same concept applies to a stock system with muffler delete and a test pipe to reduce some drone? I like the loudness, but I want the sound to come out the back, not everywhere.

speedjunky01

I was just about to make a thread on this the q300 is crazy loud with test pipe I'll try the vibrant 1st then see how that is, then I'll go to the divergence pipe.

Gern keep the divergence pipe 70mm right?

Gernby

@Weasel497 - The OEM piping has the "weiner pipe", which requires the OEM cat to reduce drone. It also has unequal length piping after the Y-pipe, which makes drone worse.

@SpeedJunky01 - I'm not sure what you're talking about regarding the "divergence pipe".

uabs2ki

Gernby - this is great info and very timely!

Over the weekend I was thinking about adding a helmholtz resonator pipe like the OEM system. My problem of course is that I have no idea how to determine the correct pipe diameter, length and placement. Can you provide any guidance or possibly point me in the right direction? Below is my setup.

I've got a 01 with a Q300V4 and oem cat. The drone was/is driving me crazy after the install. It's settled down a bit and I think (hope) it's making the car seem louder from inside than it actually is to the outside observer. Last week I had a 2.75" Vibrant Ultra Quiet installed in place of the small bottle resonator. While the drone is better, its still there. It seems to have moved down in the RPM range - more like 2-2.5k now vs the 3k+ range before. It's very pronounced when decelerating in gear.

Thanks for any help you can provide!

speedjunky01

@gern the "wiener" pipe

Gernby

Okay. There's nothing convergent about the weiner pipe. It's just a plane old closed ended branch duct.