VALENCIA, SPAIN, NOV 8 - Valentino Rossi will have important decisions to make when he first throws a leg over the Ducati Desmosedici GP11 on Tuesday afternoon. The nine-time world champion and teammate Nicky Hayden will have to decide which of two engine configurations, big bang or screamer, will be the heart of the2011 MotoGP World Championship contender. The same question was raised last year, when the decision fell to Hayden and Casey Stoner, and they went with the big bang, but only narrowly."You know, I was torn between them," Hayden said, adding "it was hard to make a decision. After the first day of the test I was wanting to stay with screamer. And then we made some changes and the last day (Stoner) kinda chose big bang and that seemed like the development, they wanted to go that way, so I went with ‘em." Last year we the team didn't have the chassis working as well, "so it made the screamer harder to deal with at times. But now hopefully, because I think the chassis is better, just the complete bike that I got a lot better understanding of that maybe it's time to try it again."Filippo Preziosi, the genius behind the Ducati race team, said the main goal of the test is to decide the firing order for next year. Ducati has prepared three bikes; one is a GP10 bike with the big bang engine, that is more or less the bike that raced on Sunday, one is a GP11 with a revised version of the Big Bang engine, and the other is the screamer. The plan is to start with the GP11 big bang engine, make minimal chassis changes, then jump on the other GP11 to start the direct comparison. Preziosi said that such a test should be undertaken in private, but that's not possible, so he asked Rossi for a favor. Rather than search for the day's best lap time, Rossi's brief is to concentrate on the two engines."I know very well that that is easy to ask today, but tomorrow without a lot of this set-up, I hope we will start in the right way," Preziosi said.Preziosi said his personal engine choice is the "one that shows the best lap time. I have no clear preference for any technical choice, apart the fact that is effective." Each engine has its pluses and minuses, but until Rossi and Hayden ride both bikes, they can't make informed decisions.Asked what his understanding was of Rossi's preferences, Preziosi said, "That's difficult." The perfect bike is usually a bike that suits a rider's riding style. "So for this reason we believe that we have to analyze again every choice we did in the past in order to suit the Valentino riding style. I can have some idea about what he prefers, just reading what was written by journalists regarding his riding style or just watching, without what happened in the race, qualifying, practice and so on. Of course, the amount of information that comes directly from the rider when he tested the bike it's really the most important."Having Rossi on his side is an asset that Preziosi is anxious to make use of, "so now we have a rider that is famous for his ability to give to the technician the right answer and we want to use that rider for that characteristic as much as we can."The possibility that opinion on the engines will be split is the least attractive outcome. The team would have to split its energy and development will suffer. "We will decide together," Preziosi said.Aside from the engine, the two areas that need the most attention are aerodynamics and the front end. Nicky Hayden has spent considerable time in the Ducati wind tunnel and he's closer to Rossi's size than Stoner; more so in weight than height."We have a different fairing, but we have not to decide in that test if we did a final fairing or not, but we have here one we will test the Valentino bike, GP11, with the new fairing, and if we have time, if we decide the engine the first day, the idea is to put that on both bikes, the engine that was preferred by the riders and to test the front fork, putting the 2010 fork in one bike and 2011 fork in the other bike, because Valentino has not the chance to test that fork in Brno at the race test, so we would like to have an answer for him about the fork," Preziosi said. Rossi wasn't able to test the evolution fork on the 2011 Yamaha YZF-M1 since it had already been decided that he was leaving the team. "But, still, even for the fork is not absolutely necessary to decide the fork now, because we have all the fork in the version 2011."Preziosi made a point of thanking Yamaha for allowing Rossi to test. The decision didn't come until the Saturday night before the October 24 Australian Grand Prix at Phillip Island."I would like to thank you Yamaha, because they showed they are very fair with Valentino and with us," he said. "We asked with them to allow Valentino to test our bike, so they did a gift for us and for me was a pleasure to meet Lin Jarvis and Masao Furusawa and to reach that result."