As Rey suggested, this is no easy calculation. I'm glad you've asked it though, as I imagine that it's an important consideration when deciding whether to relocate to Puerto Rico.
Perhaps a useful table can be found here. The table compares "Total Tax Burden" by state. California ranks 10th. You will find that is the sum of property tax, sales tax and state personal income tax. Federal income tax is of course on top of all this.
In Puerto Rico, if your salary is from mainland sources, you continue to pay federal income tax. But the "Total Tax Burden" on the island would place it near, if not at the top of the list. Island sales tax (IVU) is 11.5%. Property tax seems low (I'll let others chime in there), and there is no personal income tax paid to the island government assuming all income is earned off-island.
If however your income is from local sources, all of the above applies (high total tax burden), and you exchange a federal income tax rate of 24% for an island tax /!\ I AM A STUPID SPAMMER /!\3%.
Once again as Rey said, consult an island tax professional for more precise calculations.