OK, i think that tube is connected to a solenoid, and it comands the charcoal canister.
Something to do with the gases Surplus. All it is designed to do is hold fuel vapors so they don't get released to the atmosphere.
The vapors that were being released back into the intake manifold are now going to open air..
Spoon and Js Racing might be using a diferent system some of the times, so they can plug to a alternative gas tank...?!??!?
If this is correct, it shoulnd get any gains!! .... and removing the charcoal canister you will probably make your drivability worse.
Maybe has something to do with pressure buildup in fuel tank.
Seams quite a simple process, so its a question of trying it, and if no improvements are seen, just replug it..