That's a creative mathematical way to look at it but you're not going to get 225hp out of the 2.5L simply by slapping on a different exhaust and some software (tune). To achieve that, the redline would need to be increased (by quite a bit) and, to benefit from the higher redline entails a whole bunch of mods that go beyond a tune/pipe. It's not possible with just a tune/pipe on that engine.
The reason your math doesn't work is the 2.0L is inherently more efficient in terms of HP/liter because of factors that cannot be mitigated with a tune/pipe. The 2.5L was scaled up from the 2.0L but some practical compromises were made and the scaling has built in compromises. This is because, as you scale an engine design up, even a clean-sheet scaling as was done with the Skyactiv engine family, certain undesirable things start to happen. Peak piston speeds (and accelerations) become higher and with the extra weight of the bigger pistons, peak forces grow even faster. This is why the 2.5L needs dual balance shafts and the 2.0L does not. But the balance shafts can only cancel out the vibration, they can't reduce the peak forces of a heavier piston moving at higher speeds. For this reason the design was not scaled proportionately. The compromises were made in order to reduce peak piston speeds (at any given rpm), specifically, by not increasing stroke length in proportion with the bore. So the bore becomes larger than in the case of a proportionate scaling while the stroke is shorter than a proportionate scaling would achieve. In terms of HP/liter this might be thought of as a good thing because the shorter stroke reduces piston speeds and allows higher rpm's. However, recall that this change was made simply to be able to maintain the SAME rpm's as the 2.0L without needing to use even more expensive (and exotic) engine internals. So the rpm's stay the same and this divergence from a proportional scaling yields no improvement in the HP/liter figure, instead, it yields slightly less because the combustion chamber is not the ideal proportion for this engine design (the proportion of the 2.0L was designed to be the most thermodynamically efficient, as well as being the most manageable in terms of controlling detonation at the high compression ratio). Peak power of the 2.0L is at 6000 rpm's while the 2.5L starts to fall off at 5700 rpm's.
And of course there is the friction and momentum of the twin balance shafts that reduce power efficiency but that is secondary to the primary reasons above. Taken together, these reasons are why the stock 2.0 liter is able to make 77.5 HP/liter while the 2.5L can only make 73.6hp/liter (note: these are slightly rough numbers based on 2.0L and 2.5L rather than the exact displacements). If the 2.5L had as good of a HP/displacement ratio, the stock engine would be rated at 194hp instead of 184hp. The bottom line is that the 2.5L engine would need more than a tune/pipe to achieve 41 more hp. It's simple physics.
But it would not be difficult for a tuner to produce charts showing that much gain (and some people would believe them to be accurate). It would probably be quite profitable.
