There is a wireless chip that you can upgrade the ES to wireless if you need to down the road. I think they are about $40.

But you guys might be right that you can't turn a 20 into a W, without upgrading it to the 40-ES driver. They stopped with the making the MP-20 when they came out with the MP-10's.

EDIT-

Here is the wireless upgrade chip: http://premiumaquatics.com/aquatic-supplies/ET-RF.html

Troy- I don't believe they sell 20's at all now. They may have parts if you call them though.


Here is the MP-20 to MP-40wES upgrade kit: http://premiumaquatics.com/aquatic-s.../ET-MP153.html