I wouldn't top them. However, you can remove a couple of the lowest branch sets and remove bigger fan leaves as the plant grows and do some low stress training on them. This encourages new bud sites and helps to use plant energy more efficiently. Also, whatever you are feeding them should be about 1/3 of what you would give a photo period plant. It's too easy to build up excess nutrients in your soil. Also, if you don't watch the nitrogen levels your bud will be too green when you go to flush. Remember, that with autos, everything happens in about half the time as a photo period. Use an enzyme to help keep your roots clean and your flush will be easier and your bud will taste better. Finally, use silica to and plenty of calcium to help firm up the buds.
Happy Growing
JAS