Need Advice on Exhaust

IMO, if you really want it to sound like something other than a /6, you'll need to install a dual exhaust. A set of headers would be needed to accomplish that, then just run it like a "normal" dual system with a set of turbo's or the like, just a little smaller diameter.

Nope. I've got Dutra Duals with 2" pipes and no crossover all the way to the rear bumper, and once it's above idle, it still sounds like an inline six. A sound I happen to love, BTW.

The only way to make a /6 sound like a V8 is to replace it with a V8, as the first comment suggested. FYI, you also can't make a 4-banger sound like a V8, nor can you make a V12 sound like a V8. But you don't hear about Viper guys wanting their cars to sound like V8's, do ya?

Revel in the fact that you have something different, or swap engines.