IMO the 2.5 should be
IMO the 2.5 should be replaced by the 2.4 NA engine with the GR's 228 hp.
Subaru would, in one stroke, create a performance model with increased reliability and ultimately reduce costs because of economies of scale.
However, with their rumored move to a 1.5 and 1.8 turbo engines with possible hybrid models too, this suggestion may prove moot.