Dysturbed,
If you're looking to play way inside, the Solution Powerplus EX has a little more length and more backend than the Heat, when drilled the same. They cover similar amounts of oil, but the Soln PPEx is the better ball for a deep inside line. It's more like the Arsenal Reactive in that aspect. The Heat is an earlier, more even reacting ball. Both are pearl resins.
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"...for advice is a dangerous gift, even from the wise to the wise...."
J. R. R. Tolkien