i was thinkin about doing the exact same thing... need to do some research on it though. measure the exact size of the vent from a real TRD hood and get the right material like metal mesh etc. would be sweet though, dont know how much they run around..
i dont think you will be able to make cuts in the same places that the trd hood has because the braces or skeleton whatever you call it on the underside of the hood would be in the way, and you dont want to cut into those. you can make vents in the stock hood though, im pretty sure Mani's hood has vents cut into it and its stock.