I got the Blue Max 4X6 coil for my IDX.
On a quicky test:
I took my IDX and went out to my yard with all the settings at preset,with the 4X6 shooter coil on, and went around the yard. Next to one of our trees I got a dime reading right next to a iron reading so I marked where it was, on the ground.
After putting the 5.3 coil on, I then tried the area again,with the same preset settings,and now only getting the iron reading and not the dime, I pinpoint the iron and dig. I get a nail at about 2 inches deep, and check the area again.
I now read the dime which is about 1 1/2 inches to the side, from the nail and at about 3 1/2 inches deep, and dig it also.
_______________________________________
Will post more tests soon.