Jakup

I doubt that.
True that there isn't really any aftermarket single exhaust that is quiet. But think of it this way: most (or all) of the flow reduction in the S2K exhaust is pre-split (i.e. from the header, esp. the cat, et cetera). If you just cut the two mufflers off, or the whole exhaust from the split back, you don't really gain any power. Point being: if they continued to run a single pipe to the back, it wouldn't have lost any more power, or necessarily had to be louder.
Furthermore, I'm sure bigger, more powerful engines (hence more noise) have been made with a single exhaust that aren't louder than the S2K. And I haven't driven a stock-exhaust S2K in quite some time, but if I remember correctly the stock exhaust isn't the most quiet of production cars: it seemed tuned to have a nice, sporty sound. Thus I wouldn't say there was a threshold of sound they couldn't surpass, and the only way to do so was stick another muffler on it.

So I'd conclude it is mostly for looks, and maybe they liked the sound it made better, but certainly not necessary for the power/level of sound required.

Vik2000

Reminds me of morons putting a fake tip but during winter you only see one tip blowing the air.

RSVR

The new Mazda 3 has dual exhaust. Seeing how even the current MS3 has a single that one probably falls into the "only for looks" category.

QUIKAG

Do you realize you just contradicted your point right here? If you can cut off the two mufflers and not gain any power, then that means the dual mufflers are not a hindrance to power levels, but keep noise levels in check.

Penforhire

Muffler volume tends to define noise reduction, at least for a given design. Splitting it in two allowed them to pack more muffler volume under our cars. It has to be for noise reduction.

I was surprised when I first saw the dual exhaust on S2K's because a single would have weighed less.

Elistan

QUIKAG is right. And I think it WOULD be necesarily louder. From what I've seen with aftermarket exhausts, if Honda did a single exhaust that didn't impact power, it would have been too loud to meet noise regulation and would therefore have been illegal.

UmarS2K

The Lexus IS-F has pointless quad-exhaust mode. Just a fun fact.

Vik2000

Well... I mean aren't lots of new cars coming out come with dual exhaust? I think it's really mainly for the look, plus a polished tip.

Elistan

I agree. I saw one on the street yesterday and the stacked exhaust tips just looked silly.

UmarS2K

One of my neighbors has one. I mean, it's a gorgeous car, but the exhausts make me laugh.