Check the turbo for shaft play. Do some searching on how to do A boost leak test and compression test. Do it before you buy the car. Look around the engine bay for signs that it's been heavily modded and returned to "close-to-stock" condition. Check the radiator fins in front of the turbo for heavy bends which would indicate someone was in there changing out turbos. Check the driver side front part of the frame for holes that were cut out for an aftermarket intercooler. It's always better to find A DSM with close to no mods. Head over to dsmtuners.com and do some reading on what to look for when buying A DSM.