the turbos on the wrx's are water cooled and oil cooled. you dont need a turbo timer but if ur impatient and dont want to wait 30 secs. for your oil in ur turbo to get recirculated back into the engine then i would suggest one. but its not a must. what i do i just let my car coast to my drive way for about 30 secs. then by the time im there i just turn it off..