It's always funny how people put there blinders on when talking about real world boat speeds.
Guys, both boats are excellent platforms that perform very well on an all around performance basis. The Puma is a faster boat than the 920. It's probably not much on a normal fully loaded tournament day. I'd say average 2-3 mph depending on setup. The 920 will, on average, out hole shot the Puma from my experience so the Puma will have to play a little catch-up which on a long run will happen.
Stock boats, stock motors, optimal setup the Puma is capable of better top end numbers by 3-5 mph. However, I think those numbers get a little closer on a fully loaded out tournament rig with 2 big boys and all their tackle as said above in the 2-3 mph range.
They are close enough in top end that a poorly setup/driven PUMA will be taken down by a well setup/driven 920. That's where the difference comes in many times.
Both excellent boats again and if you want to run faster than a Cat then you should look at a Bullet, Allison, Stroker, or Gambler or in some cases a Blazer but not the 625. Only the 202. That's all folks.