I think they may, repeat may, have the same transmission. Main thing you gain w/ the 325 is hyd. deck lift. That possibly is appealing to you as me, get on or off either side. I'm not familiar with the Piranha deck. I would expect the typical 48c to do about as well with Gator blades on it - also, the 48" deck will enable you to cut closer to objects as it sticks out a little further. If the Piranha deck is a mulch-only deck, you don't have the chute sticking out on the right. Hopefully someone will step in with extra info soon - Good Luck with your decision!