HI Seb,
those seat rails are straight from the kit. They seem a bit chunky in the zoomed in photos but should look alright through the closed windows of the final build. Will have to do better if I ever get back to my doors open Evo VI. I think Renaissance have some PE replacements in one of their detail kits that look much more realistic.
Off on Holidays in a few hours so see everybody in a week or so