Do all Harley grips need modification to fit?

I've been looking for a pair of flame grips for my 1300 R and I do not like the Kuryakan ones. The flames look too fake. I saw a pair of really nice flame grips at a Harley store, but I don't know what the differences are and if they will actually fit. Any advice would be appreciated. The grips are chrome and rubber if that matters. Thanks in advance.