custom turbo

Hey guys...i'm in the middle of buying a td04 turbo off of a 1g DSM...my question is, what do i need to look for? Like what signs do i need to look for to make sure the turbo still works properly... also, do you custom turbo's are ok??? and one last thing, what else do i need to get to install it completely???i've been reading up alot on homemadeturbo.com...thanks for any advise...