Bought a used Invidia from osc this winter with the intention to modify it to reduce the dreaded drone. With the research that I did through S2ki and my local exhaust shop I decided to go ahead as I had nothing to lose. According to Car Line Muffler their rep from Magna Flow confirms that adding a short pipe perpendicular to the exhaust flow will reduce droning with out measurable hp loss. I basically copied the stock location as far as distance from the cat. flange but instead of the stock 1 3/4" dia pipe I used 2" od 409 stainless. It is only slightly shorter as the internal volume is different than the stock 1 3/4" dia. All the work was done by myself.
The only thing that I really changed was the angle of the short pipe. Instead of horizontal to the ground it is slightly elevated.
Costs of mod. = 0$ Car Line donated the 12" of 2"od 409 stainless pipe.
( they had no 1 3/4)
I machined the end cap at work.
The TIG welding I did at work. ( all after hours )
HP loss or gain?= insignificant (not measured) Invidia claims 3-4 hp so if I lost 1-2 who cares
weight gain= less than 1lb
I do have before and after sound/video clips but have not figured out how to host them. ( computer retarded )
My conclusion is: If you have to pay for this mod. don't. My hearing is quite sensitive and I can only detect the tiniest reduction in drone. Overall, aggressive sound is retained. You'd really need an oscilloscope to analyse the sound differences to see if the added pipe works. The threads on the S2000 talk forum talk about swapping the stock resonator for the Invidia mid pipe. I think it's the diameter of the stock resonator or the packing inside that gives, those who have tried it, the reduction in drone.
P.S. I never road tested. Only static test in the garage. I can't wait for salt free roads!

 

hey.. damn.. quite the handywork you got done on the exhaust

I'll host the vids for you if you like.. email it to me... (sent ya a PM with my details)

*EDIT*
Right-click, Save as....
Stock Invidia
Invidia w/ Pipe

 

Nice work, too bad it didn't make a difference

 

AAHhh my old exhaust......

I ordered it with EXTRA and very persistent drone by the way....

 

Since I was only able to put 5k km on my S last Summer I doubt, with the Invidia, the drone will bother me. I just wanted to show/prove one way or another if adding the extra pipe made a difference or not.

 

Damn...This is what I was planning to do and hoping it would tone the drone down. I guess not.

Any chance of you being able to modify the Helmhotz resonator so it can slide? I wonder if changing it will make a difference. I am thinking it won't as the 1/4 wavelengths at these freq. are quite long, but maybe it works on another principle.

BTW, nice work. You obviously welded a few things. Did you think about adding a couple of extra hangers? I found the Invidia swayyed around a little to much, so I had another pair added.

 

The hangers will be added when the car is back on the road. I'll take it to the exhaust shop that I consulted because I'd really like to have the exhaust on the car for proper location. I never thought about making the pipe adjustable. Maybe it needs to be longer? I don't know. The Magna Flow rep didn't think length mattered. The Invidia is pretty wide open, compared to stock, as far as flow goes. It's hard to determine without experimentation what will actually change the frequency and not lose precious hp.

 

 

Wait till you take the silencers out...it sound freakin' amazing about 5K. All the corvette guys complimented me on it sound when I first went out with it.

We gotta figure something out for the drone..... I can live with it as it is not my daily driver, not sure if yours is.

 

Marco, the silencers were out when I did all my tests. I do have them but have never tried them. Remember I have a CRV and my wife's got a civic? S2000 is just for dry Summer days.