if the headers are long tube there should be no problem because the cooler air cant reach the valve. shorties may let more of the cooler air up and you could possibly do damage to the guides . now if you run it with nothing on the heads for exuast manifolds then you will definately burn up the valves not to mention the wireing and paint and plastic things under the hood.

 

lol yea...u prolly woud burn eveything up..but it would sound cool... dont worry i dont plan on ever doin that...altho i have thought about making custom headers and running them up threw the hood.