Having a V6 sound better like a bigger engine will be about altering the tone as much as possible. Making it sound deeper would be the best way, so avoid big tips that amplify the tone. Make the middle section bigger, that should add sound depth.
I'd simply replace the one muffler, with two that you like the sound of the best, even if you just feed the two back into one tailpipe. The mufflers create the main sound quality, tone, while the pipes and tips etc, those tweak that sound, louder or more shrill etc. This is just my guess from reading of tons about other exhaust results and comments.
I have a 2.5" single muffler and tailpipe on my SOHC 99 Explorer. It sounds pretty good, slightly deeper and louder than stock, but it's still kind of obvious that it's not a V8. I did that in 2007 and it was a very small attempt to gain power and a better sound. I don't believe it gained any power at all from that small change, but it does sound better. There's plenty of room for two mufflers, I'd try that if I did it again.