Pension freedom rules mean there is now no maximum or minimum limit to the amount of income you can take. But you should remember that if you make a large withdrawal this will probably result in you paying a large amount of tax. You can also choose just to take your 25% tax-free cash and no income if you wish.
If you are in capped drawdown there is a limit on the amount of annual income you can take. This limit was initially based on the value of your SIPP and your age on the day the cap was calculated.