I've seen brand new Titans on the dealer lot with faded cowls. It's just one of those things with the Titan.
You've got choices:
1. Get it painted black or color matched to your vehicle. IMO...color matched looks good depending on the color of the truck.
2. Use some type of plastic protectant on a regular basis. There are several to choose from. Just do a search... My personal favorite is Black Wow.
Here is a photo of my cowl. The right side was treated with Black Wow and the left side with another brand. This was after a little more than a week of non stop rain. Unlike other trim protectants, the cool thing is that it actually beads water, so you know it's there. It's expensive but it works... :thumbsup: