You will get a little extra noise with the piston in there along with the x-valve. (found that out the hard way) It will affect capacity and superheat. The x-valve must also have the superheat adjusted. Goodman and Amana use the same x-valve for 2 differant sizes it must be adjusted for the application.
Rheem: I was told by the factory rep to take the pistons out and throw them away. They would cause a rattle and possible a whistle after unit sat off cycle for awhile.