Be careful with just checking another aircraft and comparing altimeter settings on the ground. Once the aircraft is flying, a lot of things can affect the accuracy of the reading, such as leaks in the pitot/static lines within the cabin, and the location and design of the static ports themselves. Even with a certified pitot/static calibration, if you are going to fly actual IFR I highly recommend flying next to a certified aircraft and actually comparing readings once you have had the ground calibration completed. Also do some VFR approaches and make sure that decision height as published actually looks right. No sense finding out on an actual 200-1/2 approach that your altimeter really reads 200 feet high in flight!
Vic