Well besides the obvious hood not giving you 1st degree burns;
The throttle response is neck snapping even without cold air, it's setup for low end torque above all else and will break the 33's lose on dry concrete with only a mild goose of the throttle. It's hard to say it's improved... It was uncivilized and and whip lash inducing before, a ham footed take off at a red light feels kind of like somebody rear ended you, and has resulted in more than a few people "racing" me even though I wasn't trying to (what is up with big diesel hill billy work trucks wanting to race anything else with big tires?)
60 degrees cooler intake air, by the drag racing rule of thumb (That being a 1% HP increase for every 10 degrees cooler air charge) means 6% boost in HP, which on my 4.6L stroker with bored TB, Borla Long tube headers, hollow cat, Flowmaster, TB spacer, elevated fuel pressure, and relatively high compression should translate to about 12 HP...
That's a good number considering the cost of the hood and air box were negligible using steel I had around, and about 75 bucks in premium Auto paint, (that I wish I had not used). I should have duplicolored the sides and hit the hump with black satin to match my XJ's color scheme.
To give you an Idea in this recent pic:
The grill is painted with Duplicolor Champagne metallic (factory match nearly perfect) and the hood is visibly lighter:
I could have monkey'd around more with the PSI settings when I shot paint but at 60 or 70 bucks a quart I feared running out before I had a couple good coats. So the "flop" wasn't right meaning it looks like a lighter shade from certain angles (that pic is lighter than it looks in person though).