So I drove the evo yesterday. The extra Burns muffler seemed to quiet it down a smidge at idle and cruise but WOT essentially did nothing. I think at this point I'll be swapping back on my old RMR and calling it a day. I was hoping to make it work but I think its so far off from making sound that it's not even worth experimenting. That setup worked for me for the past dozen years so hopefully it'll still be up to the task although honestly kinda concerned the tubular manifold and higher comp motor are part of my problem. Guess time will tell as I signed up for my first event on the 30th.

 

After putting a few cars together when I was younger, I got sick of the noise aspect from performance.

Over the years since, I found a number of ways to deal with noise. However, being budget minded is always a concern.
Honestly the best way to deal with this issue is via empirical testing. i.e. install a system, dyno tune it, and confirm it meets noise quality conditions, rinse and repeat.
Except this can get expensive. And time consuming.

So I usually settle on the next best thing, the cheapest option which is also guaranteed to be silent, and still opts for high performance...
Install a mostly stock exhaust system. Use larger tube diameter if necessary but keep the original(ish) style mufflers. If you have some $$ to drop you can 'upgrade' mufflers or add resonator etc... but it doesn't really matter because
A: the stock exhaust system for majority of vehicles will support ~300hp easily to begin with and
B: Install a cut-out system for max breathing (max output) situations which can further be implemented elegantly i.e. a separate muffler for cut-out side, or partially opening (multi position cut-out)

This takes care of both worlds with minimal cost. You get silent exhaust when you want and full performance/loud when you want. And cut-outs are cheap enough now (got one for $35 recently ebay auction) that it isn't an issue to replace if necessary.
meow $.02

 

^Thanks for your feedback but please reread the title as I think you are missing the point to this thread. Making an exhaust that is free flowing is pretty painless. Making a quiet exhaust is also fairly simple. However making an exhaust that flows but keeps the noise down is what I am after.

A cutout will do me 0 good bc what I am after is a solution that is quiet while Im racing to meet noise ordinances. So once again the question is what is a quiet and lightweight exhaust? Where is the middle ground as in reality they are polar opposites of eachother. The lightest systems is no exhaust at all but that would also be the lpudest. The quietest solution in theory is the one with the most mufflers and thickest piping but that will also be the heaviest of the bunch. See what I'm getting at here?

 

Have you looked into a Helmholtz resonator?

 

Thanks, yeah I've seen that video before, I enjoy his stuff. My impression of that was merely a means to eliminate the drone which is really more about a creature comfort thing while cruising. The Burns I added certainly helped cut down some noise while cruising but as mentioned WOT is a different story and I really didn't hear much of a difference. It would be wise for me to get a DB meter or at the very least download an app on my phone but honestly I know enough to know that what I currently have isnt even close to being quiet enough haha.

 

honestly how much is 20 extra pounds on the exhaust in the lowest rearmost section going to hurt? I went ultra quiet, with cat, 2 resonators, 2 mufflers, and i couldnt be happier with the volume decrease. haven't gotten any slower on track or autox and really appreciate the quiet at my age

 

Yeah, this. Id rather carry the weight of a big muffler in a place it will have no penalty on lap times and control sound than be obnoxiously loud. Thats why I went with the tanabe medalion exhaust that had the biggest can of any exhausts I could find. Turns out it fits pretty amazing also and I have not been talked to about sound since I put it on a few years ago.

 

It's honestly one of the best exhausts ever made. I'd be willing to bet it can support 800whp.

 

It does. ER made a bit over 800 with one on a 6466 car...lol

 

I believe ER made like 850whp with that system so if definitely flows quite well.

I've said this before but I'll state it again. I dont want a loud obnoxious exhaust, the quieter the better. Noise doesn't equate to more speed. I also agree that if it must be heavy its in a really good place to be heavy. Down low and in the rear, can't get any better than that on a front heavy car like ours.

That being said will 20# make a difference, absolutely not. But with that mindset then any weight reduction is pointless and we all know that isn't true. 20# by itself means nothing but do that in 10 places and now you just dropped 200#

The reality is that I didn't seek out this exhaust. My old setup was fine, but its old and tired. The Tomei popped up locally for a good price so I scooped it up but was concerned it was going to be too loud which it is. So here I am wondering if there is a happy middle ground and it seems we're just going in circles now.

I was hoping someone did something or is using something that fit the bill for sound and weight but I guess not. Oh well...

EDIT: Sean beat me to it. In fairness he's the one that told me that haha!

 

just me thinking

Hmm. Sound is waves in matter. Waves are an infinite propagation, they move and don't run out of energy because the energy is the wave. Until something can absorb the energy. Water hammer comes to mind, the faster the valve closes the more powerful the hammer.

Sound in exhaust is waves in the air of the exhaust tube. Which has been heated so molecular are farther apart than spacing at the tailpipe.

Pressure is number of molecular collisions with a given energy per time against a surface of matter, such as a tire. Tire stays inflated because number of collisions at given temperature is sufficient to hold shape.

At the head of any wave (in this case, sound) the pressure is higher and in the tail of such a typical wave the pressure is lower than surrounding.

Example
The ~40" helmholtz runner of TPI (82-92 5.7L) takes advantage of the speed of sound and time it takes for a wave reflected through the tube causes a pressure wave to arrive to the intake valve at the exact range of moments when it is open (or even just some of them). It has the opposite effect at other rpms, as catching the tail of the wave is also possible as RPMS change.

so we already know:
Properly designed tubes fit the application. OEM strive to create specific length tubes where it counts (cost effective and considered necessary). Generally by define operating ranges firstly,
e.g. A boat engine can stay 4000-6000rpm for extended periods and idle-midrange quality might not be important. In that case we would surely use speed of sound equation to create proper length header and manifold tubes with sufficient size (smaller if NA and larger if FI) for frequency of engine in that range.

Street cars on the other hand operate 1800-7000 some of them. Others don't mind going higher. It depends on the vehicle right?
So have to ask what size engine/style of driving. As soon as you say street silent with anything though- you are using OEM exhaust. There is nothing quieter. It is the ultimate in silence stealth. It can not be beat easily.

Because the OEM have used higher formula to create adequate wave cancellation in the design for that engine, the easiest and most free form of engineering design strategy which eliminates unwanted vibrations and noise. The wave in air we consider as sound may be transferred into other matter such as concrete, metal, wood etc... and when it appears in mechanical structures I am sure we've all heard of resonance failures and if not its when waves are not properly dealt with and bridges collapse.
That weird rubber seemingly pointless object bolted to some exhaust systems is probably there to prevent some form of resonance where waves get stronger as opposed to obliterating themselves or being absorbed, having a wave to release the energy in a harmless manner, which may have taken form as some kind of drone at highway speeds or whatever. My point is that some of the noise is harmless, just annoying, and some is deadly to the system, but if you really want to have highest chances to cancel everything out there are only two ways to do it properly as an enthusiast:
1. start production with/use an OEM exhaust system
2. Use engineering calculations to predict waves emanating from the engine at all frequencies and design strategy for cancellation or absorption.

Notice absorption is the rubber object on the exhaust, cancellation is tube shape/length, for example adding a tube of specific length on the body of an exhaust to reflect sound waves of certain frequencies at themselves in hopes of cancellation. The beauty of cancellation is that it is often 'free' (in the design itself). The beauty of absorption is that often it captures a wide range frequencies as a guarantee regardless of how they got there.