Our topper came sewn into a piece of fabric like a standard mattress pad, so we didn't cut it. Upside (other than the significant increase in comfort) is that my feet don't hang off the end quite as bad because the topper effectively makes the mattress just a little bit longer. Downside is that it's harder for me to squeeze by the end of the bed to get out of the bedroom! Totally worth it!
2014 Jay Flight 28 BHBE
2015 RAM 2500 6.4L HEMI, Tradesman 4x4, 3.73
Blue Ox SwayPro (BXW 1503)
Upgraded from an REI internal frame backpack and a Eureka 1/2 dome tent!