S&S/FHP will stand behind any manufacturing defect. In this instance was really unfortunate that the same customer had issues 3 times (one of which we can only surmise was damage in shipping) If i remember correctly one set was a break thru from the exhaust port to one of the head bolt holes on the rear cylinder. A feature that happend on occasion to stock cylinder castings as well, the two stock sets of cylinders in my office both have this issue. The head bolt plugs off the passage and like stock will run just fine. Since these are replicas of stock cylinders with stock ports, it can happen in core shift of the ports. We are working to add material to the casting to eliminate the issue. The loose valve guide fit was an error in supply, we had been using "no ream" rowe guides that do have a looser fit, but since rowe went out of buisness, thier fit on the last batch of guides was suspect. We have since gone with a different guide supplier and ream every guide in house to stock specifications. We strive for a quality product, but every once in a while something slips thru with these old and highly complex castings. Unfotunately like i said this customer had all the bad luck one could ask for, and i believe we did the very best we could to try to make it right but in the end, the customer just wanted a refund. We understood his frustration, and made no issue of returning his money. Going forward, we have implemented some additional quality checks and as i mentioned we are altering the tooling. Will this eliminate every chance of something sub standard getting out? Probably not, but rest assured that if you do get a substandard part, we are only a phone call away, and we will do whatever we can to rectify the issue.