The OEM version is just so-so. Galloway designed a +1 and after 2 'generations' of design pulled the product as not feasable. They upgraded for free Version 1 purchasers but ultimately pulled the product.
Superfast customer service. They make a lot of performance / nusiance-fix parts like improved trigger bars, springs, custom guide rods etc. Check em out: http://gallowayprecision.com/
Galloway Version 1
OEM:

The OEM looked good but had an interference between the extension and the grip that too often lead to the mag coming lose...amateur 'gunsmiths' got out the Dremel to increase clearance but that was a permanent modification to the weapon. I have 2 but no longer use them....