If you're trying to switch to LED bulbs just for brighter brake and tail lights, you can use halogen bulbs instead. They work well with none of the flasher issues or other problems detailed in the above thread. Specs on the halogen bulb show that they are about 50W for the brake lights and 15 W for the tail lights compared to standard 1157 bulbs which are about 27W and 8W.
Eiko Light Bulbs - H4 Halogen - 12V - 50/15W - Mfg/N H1157 - Car