super quiet? Options

[captainpyro1]

ok so this summer I'm thinking about making my car a bit more "invisible" for lack of better words, flat black, other stuff, and a new exhaust. currently i have stock exhaust, with a coffee can aerotec muffler on it, sounds great, just loud... so what specifically should i do to make it really quiet, with out hurting performance. i was thinking replacing part of my exhaust with a cherry bomb, and putting the stock muffler back on, so a grand total of 4 mufflers, i heard something about resonators, i really don't know a lot about the terms, i no it makes things quieter, and that a resonator is a kind of muffler, (absorption).

so any ideas?

[Galcobar]

Actually, a resonator is not an absorption-type muffler, it just looks like a narrow-body straight-through muffler from the outside.

A resonator, well, resonates. It's an echo chamber, bounces soundwaves off each other so as to use sound cancellation. Resonators are great at smoothing the exhaust note, and good at reducing the volume.

A straight-through muffler uses sound absorption -- it's a perforated pipe wrapped in insulation. Cheap ones such as Cherrybomb use fibreglass. Quality brands such as MagnaFlow use a ceramic insulation with stainless steel wool. Straight-through mufflers are great at volume reduction without notably affecting the exhaust flow (longer muffler = less volume), and do smooth the note somewhat.

One further point on Cherrybomb -- it's 1950s technology. The central pipe is louvered rather than perforated, so you have dozens of little scoops intruding into the exhaust stream. Theoretically they improve the sound reduction by directing the exhaust flow into the insulation and thus increasing absorption. Trouble is, this creates massive turbulence and severely reduces the efficiency of the exhaust system. Plus the fibreglass is prone to breaking down and blowing out.