From all the research Ive seen, the negatives far outweigh the positives. I believe the last couple tests I saw done, lowered overall bay temp by ~10*, but by opening up the back of the hood, pressures drop as well. You need a decently high PSID to maintain the effectiveness of your radiator. They saw a marked increase in coolant temps that would more frequently kick on the fans and for longer periods of time to deal with the heat created. Personally, I feel that if I spent all this money on your build, I wouldnt want to overwork any of it over a $10 part thats not needed.
Hell, youre in SoCal... just fashion up a CAI since there is minimal chance of water or run a highlight funnel or a NACA duct. All those last options will give you cooler intake temps without sacrificing the efficiency of your radiator.