If you guys that say it does work REALLY want your fuel to be cold/cooler listen to this.
Why don't you get a gas cooler and just put it on the fuel line instead?!
That way you will REALLY cool that fuel down.
Heck, why don't use a cooler on both lines. One on the exhaust and one on the fuel line. I'm not being sarcastic here, I'm serious! It would work pretty well!
Fluid cools (dissipates heat) better then air/gas so the small increment in fuel temperature added by the gas would EASILY be taken away if you let the fuel pass through even the smallest cooler. Take it from someone that has used Water Cooling for my PC for over ten years!