ASSEN, HOLLAND, JUNE 23: Three days after a crushing victory in the British GP, and on the eve of the 80th Dutch TT, Fiat Yamaha's Jorge Lorenzo said that he was confident but not overly excited.Lorenzo arrived for the sixth round of the MotoGP World Championship with a yawning 37 point championship lead and a lot of momentum. From Mugello, where he was disappointed to finish four seconds behind Repsol Honda's Dani Pedrosa in second place, Lorenzo rebounded with a trouncing win in the return of the World Championships to Silverstone for the first time since 1986.That win put him in a positive frame of mind for Assen, the second of five races in six weeks."It's a great opportunity that I have now about the points," Lorenzo said on Thursday in the Fiat Yamaha hospitality unit. "I have 37 points more than the second rider (Andrea Dovizioso). This is something that must give me some calm. I remember in 2006 I have 29 points less than Dovizioso and at the end I got the championship. This is a different situation, it's a better situation so I will try to take profit from it."Asked if was calmer than he was at Mugello, the first race as the leader of the Fiat Yamaha team in the absence of injured world champion Valentino Rossi, he said he was."I was not happy about the performance in Mugello and I'm happy about the performance at Silverstone," he said. "So now we come to some other track and I try to be like in Silverstone, not like in Mugello."Lorenzo and the other Yamaha riders have voiced concern about a lack of engine performance. He posted only the eighth fastest top speed in Silverstone and Monster Yamaha Tech 3's Ben Spies and Colin Edwards were both behind him. He believes the Yamaha is competitive and can win races, but he's worried about the future."Maybe at the other half of the season or maybe next season or the next three seasons, if the others have something working like that, maybe they overtake and we will be worse than them, then will be the worry," he said. The engine's strong points are the confidence it instills "on braking and in the middle of the corner to make a good performance."