I wish I could say flawlessly also. However I had to sand the rust off of the mating surfaces. Also they knocked a few little dents in them. It wasn't a huge deal but it did piss me off. It just took a little time to fix. It was a busy time of the year though before race season that I sent mine off. That was probably a mistake because my dad's cylinders looked great that they did. Be aware that they chemicals do take the black paint off of the cylinder, so you will need to spray paint it back. One other thing, be sure to take absolutely ever single thing off of the upper crank case before you send it to them, they may not take it off in a good manner (ie they pryed a piece off and ruined it on my 10 case). Luckily that part wasn't expense. It was just a little splash plate or something.+1, I sent a couple sets of R1 cylenders to them and they always came back flawlessly.