More info is needed. You state pressure is the problem, but I am assuming that it is actually a water flow problem rather than low pressure, unless you have actually checked with a pressure gauge. Is the problem in all of the hot faucets in the house, or just at one location? Is this a condition which suddenly appeared, or has it gradually occurred over a period of time? If it suddenly occurred, has some plumbing work been done recently? Have you checked the shut-off valve at the water heater and at the offending faucets to ensure that is fully turned on?