Replacing flashers and stop tail with led

Does any one know if this can be done as I Am hoping it might improve the output of the indicators?
Not sure if you need to buy a bulb with resistors built in or do I need to install resisters in the circuit?
also as the draw off will be lower its been suggested that the flasher unit will need to be changed to an electronic one as the present one is a thermal design? If so what can i use to replace it as the 2 pin design is not a common on ...least i cant find many of them suitable for Led draw off..although i am aware on the circuits on this bike the power also goes through it i believe?
On line it seems to suggest a 4 w led will replace the 21 w std flasher bulb but not sure for stop tail..any ideas please?

Talk to Paul Goff http://www.norbsa02.freeuk.com/ he specialises in LED bulbs etc, you will need a special flasher unit if you go LED. From looking at Paul's web site it looks as though only 12v LED sets are available.
Incidentally the standard Townmate flshers bulbs are 10 watt not 21 watt, these were only fitted to some very early bikes but the drain on battery was too much & they did not work very well.