The Nissan R390 pits at lap 14 because it's running harder tires than the Mazda 787B. This shouldn't matter in the long run, since the Nissan is slower, right?
Again, it comes down to your driving, mate. Learn this track well, and you'll succeed. 700 horsepower + T3s in a Tommy should do the trick. And if not, you can still run super-hard slick tires (T2) rather than hard slicks, and get a few extra laps in.
There are plenty of times at Cote where you're missing a wall by inches, or even grazing it, but DON'T get into the habit of slamming them. Slamming walls seems like a good idea, but in reality it is only slowing you down. You'll get better, more consistent lap times once you learn this track's odd braking points and how to navigate thru its weird corners, hairpins, chicanes, and L-turns without running into any walls.