Shouldn't your post also be favorite XC and XR parts since they are the same bike but a Magnum is a XC just like a XCT is a XC with a trunk and a few extra parts? Back to your question, my favorite thing I have added to my XR is the heated grips (standard on the XCT). Makes riding in 35 degree temps much nicer.
2011 Cross Roads Sunset Red
OEM short windshield, passenger backrest, crash bars, saddle bag bars, heated grips, vinyl closeouts, tachometer, ambient temp, LED headlight, luggage rack. WD lay down licence plate.