quick question
 

http://c2.api.ning.com/files/bnJSKgC.../ShellGas1.jpg

the dirty valve... supposedly intake or exhaust?

i'm writting a paper on the integrity of this claim due at 8:00 a.m. tomorrow lol.

I'm gonna take a shot in the dark and say thats an exhaust valve by how dark it is lol

EDIT: And the "dirty" valve looks more like a car that was burning tons of oil

that's what i'm thinking.

It's usually deposits on the intake valves that affect performance and about what alot is researched. You really have no sure way of knowing if it is an intake or exhaust valve without seeing the other corresponding valve, ie: intakes are larger than exhaust.

Nitrogen enriched gas sucks, all it does is lean out you're motor and make already shitty gas, worse. pure speculation on my part, but the valve on the right looks bigger.

i just wrote the paper assuming it was an exhaust valve. i'll let you all know what grade i get :)