Actually, I'm pretty sure it's Yakuza Strike and not regular MB that lets you play through the Throwing Spikes again. I could be wrong though since the JM I used to crank out big scores on is no longer around so I haven't played the game in a while. You can actually double stack the hold bonuses by getting Hold Bonus from both the matrix and the fifth Throwing Spike award. They will stack, meaning that you can carry the first ball's bonus across three balls. I don't remember whether or not getting another Hold Bonus on the next ball will hold the first ball's bonus, but I don't think it will. Additionally, there is a bug in the game where your held bonus is actually awarded twice (first on the "Held Bonus" screen, then again on the "Total Bonus" screen) per ball. Combine all these things (4X bonus, double bonus hold, massive spinner millions) and it's not impossible to see scores well over 200 billion.