The other thing is if you swap 1 thing at a time (like I just did on the heads, and how I like to do it), it takes forever to get it to the track because of schedules. Also, it cost a whole lot more.... I paid 40 bucks to get on the track, then gas and food. Between scheduling and money, I almost can't do a "change one thing and make another pass at the track". But I did it on the heads.