I installed hood louvers on my 2005 LJ last spring. I was experiencing the heat soak issue you mentioned, especially in the heat of the NC summer and when slow going on trails. From what I understand the louvers do nothing for actual engine temp but reduce the heat in the engine bay area, which can help control the heat soak issue. So this is in no way scientific, but this summer I had no, none, zilch, nada... as in zero... heat soak issues. I used the genright ones, but same principle as the poison spyder. If I were to do it again I would probably go with the poison spyder for ease of install.