I tend to agree with the above comments but to answer your question, I have some experience with the x-2 on my race bikes. First, I used standard tappets and if you are getting a new cam, have Mega reface them for you. At first, I made the mistake of setting the cam a couple of degrees retarded because 'that's what you do with the 473'. It sucked! Reset a couple of degrees advanced. Result, a small amount more power in mid and upper range. A couple of horses. They say stock springs are ok but if you are going to the trouble get new ones. Ed V. sells good springs that are not 'race springs'. Real 'race springs' require a lot of maintenance with valve lash. So, if you are building a street bike you don't 'need' a different cam but get new springs and set to spec and check to make sure cam is set to spec on all 4 lobes. However, if you want to make sure everything is tip-top then get the x-2, springs, etc. and then spend a few bucks on dyno time for a good tune. Hope this is helpful. PM if you want more info. PRT