Well...someone would need to actually hook up temperature readers to my car as well as a stock 370z. But it is really impossible to tell, since I have a variety of extra performance parts which could have possibly raise temperatures under the hood compared to a stock 370z with the seibon hood. All I can say is that when the car is running and up to operating temperatures, you do see a lot of that "heat haze" coming from the vents, more than I had ever noticed with the stock hood. So I am assuming that it lets a lot more heat out than normal. But I highly doubt this affects performance in any way at all. But I will say...it looks damn wicked!!