Well I have run a two seperate exhaust identicle side by side, I have run a two header into one pipe setup, I have run a dual axhasut with the Xtype crossover and I have run one with the H type cross over. I didn't like the H type at all. I liked the X and the identicle dual side by side the best. Both seemed to produce more bottom end than anything else. The two header into one work well everywhere. As for which is the best. Not so sure one is. The differences are not as great by the seat of the pants feel as you would expect. The biggest reason I disliked the H type was the sound. The best sounding exhaust of them all is the two into one type. But I have won equally with each setup so can't say any of them perform bad.