Not a good start that you have had there, i sell second hand parts and its a flaming nightmare to be honest. particularly turbos, i have sold turbos that i have been out and test drove, they have boosted perfectly, no smoke and as such have been advertised as so. sometimes when people inspect second hand turbos though, particularly specialists, they identify things inside the turbo that your average person wouldn't see, this is when it becomes tricky as the seller says it was working perfect (and why shouldn't they) but the buyer said, well my tuner said it was pants (and why shouldnt they). the difference with buying from somebody you can trust thought is that they will work with you and not have your pants down.