I don't know but I have xforce 4-1 and I love them, I think that 4-1 system is best for dohc-vtec engines because they give you good mid to high range (that is where real power is and where you can make good improvments, plus you pick up a bit in low range as well), I love my ITR because of it's high reving engine if I wanted something with low to mid range I would go for something like pulsar SSS, golf VR6 and so on.
I think that jap ITR came with factory 4-1 headers so that is a proff of what honda thinks is best for those engines.