The head gaskets are not as much of an issue as in the XT as they are in the normally aspirated engines. Is the XT you are looking at a 2.0 or a 2.5 liter? The 2.5 liter turbo engines have a few very serious bottom end issues if the car has been modified or run very hard. The pistons are known to crack under hard stress and cause severe oil consumption. A thorough leakdown test should be done.