These are the best modifications I have made to my set-up. When we figured this out, my wednesday garage golf group LOVED how the system felt. The system is GREAT straight out of the box, but these modifications improve the FEEL of using the unit.
1. Tear off the green turf that comes with the machine and use it as a template to cut medium shag carpet to replace it. (You can usually get small pieces for free from carpet stores) Trim the shag carpet around the sensor areas a little more open with sissors and apply a small bead of hot glue at the bottom edge to prevent fraying of the edge. Apply velcro tape to the bottom of carpet and stick onto unit.
2. DO NOT CUT A HOLE FOR THE TEE. Instead use a Felt Marker to mark the old location as this is the best ball placement location for the sensors.
3. For a Tee, take the rubber tee that comes with the unit and place it on top of the Felt Marker dot. Trim the tee to a proper level to be used for drivers.
HOW DO YOU PICK THE RIGHT CARPET? - Bring a 7 iron with you to the carpet store. Swing through a couple different types of carpet. You will know when you found the right one as it will fee like swinging through fairway grass.
P.S. The same carpet makes a great lightwieght driving matt. I did this becuase the green matts are pretty heavy and do not store easily. I applied the carpet to a 5/8 piece of plywood with carpet tape. Works Great, using a felt marker and a straight edge, I transposed some alignment lines onto the carpet.