I see noticeably warmer trans temps with my billet grill in place. It's up to a 20F difference. I keep in in OCT-MAY for reduced cooling and also rock protection, then remove it for the summer towing season.
I have a trex billet grille on my 01 E350,what I did was take a old antenna and mounted it to the hood relase latch ,the end of the antenna sits above the drivers side headlight, I put a piece of rubber hose on the end of the antenna,all you do is pull the antenna to the right and it opens. Hope this helps