Both setups will work fine with your car. Our little 3.8s don't put out enough power where the y-pipe is deemed inefficent. The main difference you'll have is sound. I went with true duals with out a crossover. So, I can't really say if the y-pipe or x/h-pipe will sound better. Exhaust tone wieghs heavily on personal preference.
Basically, get which ever setup you want. The x/h-pipe setup (True dual exhaust in general) is really only necessary for heavily modded engines. I'm a assuming the y-pipe is cheaper and in most cases is all people will ever need. So if you want to spend as little as possible, go the y-pipe bolt up. You should be able to do that setup in your own garage or driverway. If you want duals you're going to need to go to a shop and have them cut and weld it up for you. Unless you know what you're doing. I think you'll like the sound you get either way and what it really comes down to is how much do you want to spend.