Chambered mufflers? Options

[dawnoforigin]

Is there any positive experience with these types of mufflers? I know most go with the straight through design, but I know they would be way too loud and not sound the way I would like. I also was considering this because I don't want to lose any low end power by getting a straight through design. Low end is much more important then high end to me. I was thinking about looking into a Dynomax Super Turbo or possibly a Flowmaster. Any input is appreciated.

http://www.dynomax.com/superturbo.stm

[Galcobar]

Cars do not need backpressure -- it's a myth.

Big pipes have lower initial backpressure, but quickly create turbulence (a form of backpressure) because they let the gas expand, cool and slow down. Exhaust therefore cannot exit the engine as quickly and efficiently, and energy that should be going to turning the crank is instead being used to push exhaust gases out.

Backpressure is an inevitable consequence of not having a variable exhaust size. The harder the engine is working, the more exhaust it needs to get rid of, and the ideal situation would be for the exhaust pipes to grow as the engine pumps out more fumes.

Since we don't have that technology, what we do is pick a compromise size. It's not as efficient at low revs as a small pipe, because the exhaust gases have room to expand, cool and slowdown, reducing the scavenging effect and forcing the engine to expend energy on moving what is now heavier gas. At high revs it's not as efficient as a larger pipe, because the gas bottlenecks. Either way, you get backpressure. The compromise aims to minimize that backpressure over the band, and preferably have the most efficient exhaust extraction (high velocity, lowest backpressure) at the RPM point where the engine spends the most time.

Really big pipes are good only if you're producing enough exhaust to be efficiently using them. This is where FI and NO2 come in, since they effectively simulate greater displacement and therefore a bigger engine.

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Boss-celica, given you have a 5SFE, unless you've replaced your stock manifold with a header, your cat is still attached to the bottom of the manifold. Besides which, the term "high-flow" for cats doesn't really apply except between modern three way converters and older styles. The Celica comes with a TWC.

If you have a header and are running without a cat, my best suggestion would be to pick up a cat with a resonated core. That way, when you install it in place of the stock resonator, you retain most of your sound suppression and keep your emissions clean.

Straight-through mufflers are louder than chambered or baffled mufflers. However, their design allows you to use a longer muffler without particularly affecting exhaust flow, while significantly reducing noise. Just don't mistake an old-technology glass pack such as a Cherry Bomb with a modern straight-through muffler. And don't mistake a resonator for a glasspack or straight-through muffler. Resonators bounce soundwaves off each other to cancel out noise, glasspacks/straight-through mufflers use insulation to absorb noise. Entirely different technologies. Resonators get rid of buzz better than absorptive pieces, BTW.-