Getting a new Si

[Civic_RedLine]

Ok, Ive been searching for an si and about 2 private sellers should accept my civic 2001 as a trade in. One has 75k mileage with salvage title and the other had 112 mileage and had a clean title.
The one with the salvage title had too many dents and color was faded. The clean title one just had a loud engine and took like 5 seconds to start the damn motor.
What I wanted to know is what else to look for when testing a vehicle's condition.
Any advice would be appreciated thanks!