I built my RV-12 between 2013 and 2016. My KAI makes no mention of trimming balance weights or balancing the horizontal tail. I have flown it with the weights as delivered for 6 years and 424 hours. I taught aircraft stability and control in college for many years and understand balancing, but I have no complaints about mine as is. I can't help feeling this balancing process is not really necessary. I have the SB parts but am still undecided about how to accomplish it.