X or H
Realistically they are about the same, but I guess dyno results usually favor the X by a small margin. I would recommend listening to both I've had an O/R H, and an O/R X and I liked the sound of the X better, thus I still have the X, sold the H. Both sounded good I just liked the X better. Sounded more "exotic" is the only way I can describe it...
this is all up to you... half of us like H the other half prefer x..also i have heard a lot of people say that x will usually give you only 2-3 hp of H .... i personally love the sound of x it seems louder to me... h seems to be a little deaper... good luck


