There's a ton of theory into the exhaust systems, but in general an H or X pipe is largely for sound. Unless you have the resources to try multiple locations to find which one actually can help torque, you're just putting it there to mix the exhaust tone from both sides which usually results in a smoother, more pleasing note. A true dual split system will work just fine but the pulses never mix until they leave the tips so the sound is different. Not bad, just different.
A properly placed X pipe (in terms of how far from the header collector/exhaust ports) can gain some power/torque, but it takes trial and error and depends on how the rest of the system is built. It's all about wave speeds and harmonics, lot of great info out there if you want to research.