I think they are using a volvo 2.5 turbo 5 cylinder, not sure if its the same as the s60r motor but that produces 300 hp stock. if it is the same motor as out of a volvo then its safe to say the motor will have no issues because volvo has been using the same 5 cyl turbo motor forever.
aftermarket i think is plentiful because it shares a motor with volvo and there is a good amount of tunning for them.
if it were my choice i would do the widebody wrx, they look better and awd ftw