What amp would i need for 2 jbl gt5 12" subs?

The RMS is 275, so the peak doesnt really matter. You need a 500-600 watt RMS amp. They are single coil 4ohm woofers. So you need a 2 ohm impediance performing amp. The kicker i listed in the source will do you good. Wire them in parallel, which i have showed you in the diagram in the source. Use 4ga amp power wire and ground, use 8ga speaker wiring.