Yes, KMO's fenders are very good. Quality and fitment is on the higher end of the scale when it comes to FRP automotive products for these cars. They're actually produced by TRA (rocket bunny) except these are made in much lower volumes, at much higher prices. So the moldings used for these fenders are always spot on.
I have many friends who have bought these across the world and every single one of them have said that fitment has been direct bolt on with no issues whatsoever.
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ft86me in response to your question, you will want the extension piece to fit the vertex side skirts on. If they were just a bottom mounted skirt that didn't wrap around the fender, you'd be fine without. But unless you want to do some fiberglass work to the skirts, I'd recommend getting the extension.