Cologne's red and white F1 car, not expected to particularly suit the bumpy street layout, is wearing the aerodynamic innovation in a intense hunt for extra downforce.
Trulli, who then drove for Renault, last year won his maiden grand prix at Monte Carlo.
He admitted to La Gazzetta dello Sport, though, that the relationship with Flavio Briatore - in late May, 2004 - was already starting to crumble.
"This year my mood is different," Jarno told the newspaper. "I'm extremely happy and we might surprise everyone." -GMM