So dumb question I have to meet a hard capped 107db this weekend in the Cobra it is at last check ~115-7 db if I keep my foot really out of it. I remember as a kid stuffing stainless steel wool in the glasspacks of my mustang to get it to pass inspection and it was unbelievably quiet, the stuffing blew out on the way out of inspection 
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How terrible would it be to take a bunch of loose SS wool packing and just jam it in the side-pipes and make a little screen on the end of the pipe that keeps it from getting blown out for track days. Couple HP loss is not a big deal, exhaust pipes are out in the wind so they should stay pretty cool, less then 350F according to our temp gauge. Its that o I cut the pipes apart and put in a spiral with stuffing and then it will be quiet all the time which is not my cup of tea.
Why don't you just get a pair of side pipe baffles?
http://www.summitracing.com/search/department/exhaust/part-type/muffler-inserts?N=4294948820%2B4294910238
Can you put on Super Trapp style ends as a way of keeping the wool inside?
Most spiral mufflers are actually very restrictive, there's no free lunch with them.
I was also thinking about bolting on a Supertrapp end.
Edit: Maybe coupled with one of those inserts (may have to try those myself)
Clamp some turndown tips on the end?
Tried steel wool with my FSAE team to pass sound back 10 years ago, we used too fine of steel wool, it fused during the enduro and became something of a butt-plug with bad results (throttle response lagged to more than a half second according to the driver).
If you do it, use the type that you scrub dishes with, not the type you would use in a finishing operation.
EvanB wrote:
Clamp some turndown tips on the end?
Already have those installed. It is defining without them, did not think they made supertraps in 5 inch widths might have to look into that.
or get the stuff that Burns Stainless sells
stafford1500 wrote:
or get the stuff that Burns Stainless sells
That is what I was thinking of getting, though the spec Miata people as swearing by the large loop stainless steel scrubbing pads that you can get at the store for cheap after the exhaust in the turnout. That would be super easy to do and I can get it done before tomorrow.
Are you sure your outlets are 5"? I've never seen any that were larger than 4".
Also, I used to work for a sister company of supertrapp and they sponsored my race car. As such, I spent a good amount of time on their dyno. I can tell you this about their mufflers - They can be quiet, or allow the engine to make power, but not necessarily both at the same time. 
wearymicrobe wrote:
stafford1500 wrote:
or get the stuff that Burns Stainless sells
That is what I was thinking of getting, though the spec Miata people as swearing by the large loop stainless steel scrubbing pads that you can get at the store for cheap after the exhaust in the turnout. That would be super easy to do and I can get it done before tomorrow.
The cheap fast option gives you the chance to try it before you purchase and wait for the expensive stuff... I would give it a try. In fact I may have to on a car that I am building with side pipes. No matter how I approach the noise issue, I can't get the low frequency reductions I want (lack of real estate in the exhaust).
44Dwarf
UltraDork
4/24/15 1:06 p.m.
Tack weld a washer a few inches down the tail pipe or cut the top off a soda can hose clamp it to the tail pipe and poke holes until you 1 db below the rule....BTDT
44Dwarf wrote:
Tack weld a washer a few inches down the tail pipe or cut the top off a soda can hose clamp it to the tail pipe and poke holes until you 1 db below the rule....BTDT
That actually sounds like a staggeringly easy thing to do. Will report back tonight.
A standard can will just fit over a 2.5" exhaust, it's 2.6." Apparently a Monster tall can is 2.5" so it might seal better.
The Monster "BFC" is bigger.
