What would be a good PSU for this build?

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Core i5-4670 3.4GHz Quad-Core Processor ($209.99 @ Newegg)
Motherboard: Asus Z87-A ATX LGA1150 Motherboard ($129.99 @ Newegg)
Memory: Corsair Vengeance 8GB (2 x 4GB) DDR3-1600 Memory ($79.99 @ Newegg)
Storage: Samsung 840 Pro Series 128GB 2.5" Solid State Disk ($114.99 @ B&H)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($58.98 @ OutletPC)
Video Card: Gigabyte Radeon R9 270 2GB Video Card (2-Way CrossFire) ($203.98 @ Newegg)
Video Card: Gigabyte Radeon R9 270 2GB Video Card (2-Way CrossFire) ($203.98 @ Newegg)
Case: Zalman Z11 Plus ATX Mid Tower Case ($44.99 @ Microcenter)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($88.98 @ OutletPC)
Total: $1135.87
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-01-07 16:03 EST-0500)

I'm going to crossfire those 2 cards.