A little over a year ago I made a cover to go over the stock grill . It blocked approximately 30% of the opening. Everything went well even in 90 plus degree weather. Then I got caught in a traffic jam from a accident on a 95 degree day , after about ten minutes of sitting still it started to heat up . Just couldn't pull enough air with the fan . Luckily traffic cleared just as the light began to flash . I was able to get back up to speed and it cooled back down . When I got to my destination I removed the cover , just wasn't worth the risk.
I now have a different setup that I made to go in front of the stock grill.