well the rule of thumb is normally true dual shorty headers will give you that nasty V8 sound everyone longs for. Long tube headers (full length) will give you sound and performance. Though many people will attest that shorty headers sound "SLIGHTLY" better. They both make good sound.
It depends on where you're going with it. Going for performance, get long tube race style headers (PPH or GSM - either will run you about $700+ with shipping), they sound very nice too, don't get me wrong, So you get the benefit of sounding nice, while getting the low restriction performance. But you get the unfortunate side of forking out ALOT of money for minimal performance gains (8-12rwhp in most cases).
If you just want the sound and want people to marvel. Go with the Gibson shorty headers. Shorty headers sound great, but performance is lacking. Most of them don't flow much better than the stock manifolds. I believe you're looking at about 3-6rwhp with those. But the price is right in most "less rich" people's pocket books. haha.
Last but not least, you want insane sound, you want to get a camshaft. That's gonna be your main sound producer. I have a 210 cam with .510 lift and Gibson shorty headers, and the compliments and amazements I get are endless. But camshafts(nice ones) normally require a lot of other mods to compliment them and make them work right. Good luck and Have Fun! :banana2: