im sure u dont plan for your son modify the car for speed so i say you should get him a 2.8 becasue even if he wants to modify the engine there is nuthing he can really do
2.8s are more relible then the 1.8Ts, the 1.8Ts have alot of issues with oil sluge
the 1.8T becasue of the turbo u have to baby it and stuff but the 2.8 can take a lil
more punishment