I recently fitted side steps to my 2007 RRS.

The kit did not come with precut sills and I had to cut the existing ones. This proved a time consuming job as I had to cut and trial fit many times to get the sills to fit around the new step brackets without removing any more material than necessary.

The front bottom corner of the rear door - even though opened - gets in the way. I struggled and managed but I wonder whether removing the rear door (or the bottom hinge) might not have been quicker.

Having done one side, the other was easily copied and went very quickly.

Anyway, I have a paper template made and I drew up a dimensioned A4 page diagram of the cutting needed.
If anyone wants it, I can post this diagram. .
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Come for a visit, Victoria is beautiful!