Look at this exhaust and for application how would it behave?

This is the Seeker exhaust on a s2000, perhaps even more overall pipe length than the original exhaust single to Y dual. What it is missing from the original exhaust is the OE helmholtz chamber but it has a total of 3 mufflers just like the oe unit. I'm thinking if 2.5" mandrel it'll maintain solid exhaust velocity mid-range rpm and drone much less than a conventional dual or single. 

That 2in 2out muffler loop on the left is most intriguing to me on this application.  Will any non direction 2in 2out be fine I assume? 

 I plan to perhaps custom 2.5 mandrel all the way with something similar. 

My current set up is ballade tri-y header 4-2-1 > hiflo cat > 3" berk techology exhaust with a 3" vibrant ulta quiet resonator and a branched helmholtz muffler/resonator made with a old small canister similar size to OE s2000 middle canister.

On karcepts STR tune for 04-05

I'm going down to 2.5" to be quieter inside the cabin and to have a better mid range. Will consider having just the 2in2out and a side branched helmholtz chamber to maintain good exterior noise and tolerable interior drone.

The extra length of the exhaust can work against you in A weight, and B more parastitic losses.  Most drones ive found have  been in the 90-135hz range, which require cans of considerable size.  

If it were me...Id probably run a midpipe with a Vibrant UltraQuiet and then a single tailpipe with a resonator tuned to whereever its droney.

If you want to get blown away look up ASM Siren exhaust. 

Yeah that seems like backpressure city. 

OP screen name.... muhfuggin hilarious. 

My set up currently already has a Vibrant Ultraquiet. I don't think the back pressure would be too much considering mandrel bend 2.5" it might have good velocity at mid-high rpm especially considering I am running a tune. I doubt Seeker would do anything to jeopardize drivability of any car and overall length of piping is probably just a little more over OEM single to Y.

I've considered ASM before but for price and performance the EVS would probably be better suited. 

Glad you like the name Vajingo haha.

Not just any reversible dual/dual muffler will work. Many have an X crossover inside that I would expect to be rather counterproductive to flow in the pictured setup.

For other thoughts, it would really help to be able to see a pic of your current cat-back...Or at least axle-back.

I'm not sure shrinking your exhaust pipe size will have any benefits besides weight. I'm hoping one of the experts here chimes in, but my understanding is that reducing pipe size will have zero impact to power, until you start restricting flow. Backpressure is never a good thing (on a 4-stoke, before any ring-a-ding-ding fans chime in ).

Driven that is correct, hmm not sure who makes a non direction and non x dual in dual out.

Most likely I'll leave mine alone rather than throwing more cash down.

@snow yes from experience shrinking down the exhaust size would decrease interior drone a slight bit and the expense of some power.

Not sure how exhaust pulse velocity and acoustics work but it just does so maybe some exhaust legend will chime in. I've ridden in a js racing 60rs (2.5) and a T1r (2.5) before and it seemingly droned much less than the 3" with 3 mufflers. Basically louder outside quieter inside. 

Even when I had a UK mod with resonator delete was louder than my exterior currently with less drone inside 

This is my current set up, easiest way to show it without lifting my car.

It looks like they did it that way mainly for fitment reasons. If they could have I think they would have fit the dual inlet/outlet muffler right behind the rear end and lost about 5' of extra pipe from the exhaust. Not to sure if I've ever seen a dual muffler be able to operate that way. Is it possible they made it inhouse for this application?

The exhaust wizard did chime in.

Larger is always going to favor lower frequencies vs smaller.  That be...large (or small) for given HP capacity.

I agree to many of posted terms though at this point now just entertaining the though of going back to a 2.5" to reduce interior resonance.

I am sure there is a reason for the odd muffler set up.  It's obviously a system that is not set up for maximum power.  

I'm no expert on the matter, but intuitively I'd guess that a muffler would make a pretty terrible Helmholtz chamber.  It's sole purpose is to dissipate the energy entering it, rather than reflect it. Even if you have completely gutted it, which would probably be more work than simply building a chamber from scratch, it's apparently tuned to the wrong frequency.

Before throwing it all away and starting over, here's what I would do:

1) Download "Spectroid", or some similar sound spectrum analyzing app, onto your phone.  This will let you see the specific frequency range(s) of your drone.  As malibuguy noted, expect it to be centered somewhere around 120Hz, which correlates to the roughly 3600 rpm range on a 4 cylinder.

2) Do the math on a 1/4 wave tube (often mistakenly referred to as a Helmholtz) resonator for this target frequency. Pointing an IR thermometer at the current 'Helmholtz' muffler after a healthy drive should give you a reasonable idea of around what temp to use for determining the adjusted speed of sound. Expect the final results to be somewhere around the 29-35 inch range

3) Install a side branch tube with capped end of the calculated centerline length extending into the considerable exhaust space left unused by going with a single.

If it works, great. If  not, you've lost little by trying.

.

Alternatively, you could contact Good-Win-Racing and see if they'll sell you just one of their (real) Helmholtz resonators without the rest of the mid pipe. Probably not, and if they do it'll probably be not-cheap...But you can't know if you don't ask.

In my professional experience, 1/4 wave resonators have a very narrow effective range, basically they only seem to work at steady state cruising.  Any load beyond cruise throws them out the window (like say in gear but going up a hill).  Its fine if you have a dead on cruise speed and its you have a problem spot.

Helmholtz resonators seem to work at that frequency regaurdless of load (with a little bit on either side with a tapering effect).  And the size can be manipulated for effectiveness.  There is essentially infinite ways to contruct a Helmholtz resonator to operate at 1 frequency.  However, I have played around on my personal vehicles to confirm the theory.  To keep it brief, the largest form of chamber you can build with the largest feed will have the most effectiveness, which does seem natural.  However I wanted to see if space dictated a tiny can with an even tiny-er feed to bring the frequency down to where it needs to be would be as effective.  No it wasnt...I about halved the difference.  But it does work still. 

Say you have a strong drone at 90hz...and another "note" at 135hz, you can prioritize your availible space for that 90hz can, then sneak in a little frame can to round out your sound.  Which is essentially is how my daily driver is set up.  I have 1 tiny, packed resonator to fitler out the high frequencies and then 2 tuned helmholtz, which leaves me a beautiful note that still barks outside of the vehicle while disappearing when I need it to.  My 2 other cars (that run) have smaller frame cans just to polish out some notes I didnt want.

Cool thread. Unfortunately i think most people who don't follow Malibuguy on instagram are lacking context on his range of experience in this area. 

Vigo (Forum Supporter) said:

Cool thread. Unfortunately i think most people who don't follow Malibuguy on instagram are lacking context on his range of experience in this area. 

I also only post about a 1/3rd of what I do lol.  But usually with my cars everything gets posted because it helps me keep track of everything Id say id remember ha

Link to your insta? Very interested.

But usually with my cars everything gets posted because it helps me keep track of everything Id say id remember ha

The only way i remember when i did anything on my cars is by looking at my pictures and forum posts, lol.

Pipe Dreams Fabrication 

In reply to Vigo (Forum Supporter) :

My shop IG has some weird block for the last 2~months.  It wont show my caption or to allow me to comment on my own post or others.  Plus it wont let me like posts.  Freaking weird.  So I stopped posting much because w/e

Definitely appreciated info dropped in on here. Thanks