Originally posted by Owen Thomas:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Is there a way, (dynamically) without raising temp per say, ... that one could increase the speed of sound?
Nope. You can increase the gas velocity by making the pipes more narrow, but the local speed of sound is described by gas properties and temperature. If you want to inject helium into your exhaust stream you could, but um, probably not worth it.

Just for clarity, a tri-y exhaust system is usually a 4-2-1 merge (three 'y' collectors), while the one you linked a picture of was a 4-1 merge collector. Also, what do you mean by a "180 degree header"? Do you mean pairing the primary collectors for 180* crank offset, or just a u-pipe? </div></BLOCKQUOTE>

180* offset, and there is more than one kind of tri-y but generally yes, 4-2-1.