i have a 1992 subaru impreza EJ18 and would like to put an EJ20 engine and would like to know if i have to modify the mountings and also change the computer box and wiring
No, you should not have to modify the motor mounts, ej18 and ej20's use the same ones. As far as the ECU and Wiring harness goes, it depends on whether or not they are the same motor as far as SOHC or DOHC and what year the EJ20 came out of so some more info would be helpfull.
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