You will always get horror stories, but you have them from all tuners/engine builders too. If you do it your self and your not sure on something you stop and do some extra research, i always say to myself if im going to do something im not going to set a deadline as thats when things go wrong rushing get them finished. Im a perfect example, my first 4efe i changed the head gasket after replacing my valve stem seals, but didnt torque it down properly as i didnt ask enough questions and i wanted it done. it blew through as you'd expect. second time around it was fine as i knew what i was doing, still cost me less than having it done at a garage once and i learnt my lesson