i have a mag 9.5 that has 1 1/2in. plumbing on it. what alot of people along with me didnt/dont know is that you have to have a certain size pipe for the mag you have. if you still have the box and info on the pump still, read it and it tells you what size you should plumb the pump with. if you dont plumb it with the right size it will not get its max flow. i hope this helps you out, let us know how it turns out.
mike