You won't see any difference except for maybe excessive water pressure. Be sure to install a water pressure gauge, even if it's just a temporary one, to verify the pressure.
Hpy is looking to go blown, so a crossover should be used. At the most, you'll gain 10hp. You'll also run into water ballance and temp problems. I can't it in your pic, but the crossover MUST have a bypass. That's the only way you'll ever build heat into your engine.