As Baltimore Running Festival organizers considered changes in the lead-up to Saturday’s morning of races downtown, they seemed to borrow an idea from the runners themselves: It’s not how you start that matters. It’s how you finish. It was an idea small in scope but big in impact. Patrick Sullivan noticed it right away. As he came down Hopkins Place and made a left onto Pratt Street for the final tenth of a mile in the Baltimore Marathon, as he saw the finish line in the distance and heard the blast of cheers and clang of cowbells on either side, he thought of maybe the country’s most famous marathon. “It's kind of like that turn onto Boylston Street,” the Catonsville resident, 28, said, referring to the iconic final stretch of the Boston Marathon. “You hit that turn, and it just erupts.” In rerouting the races’ endpoint from the parking lot between M&T Bank Stadium and Camden Yards to Pratt Street, the Inner Harbor not far off, officials had hoped to make just that kind of lasting impression. After as many as 26.2 miles of pounding pavement and perfect weather, it was a special kind of runner’s high to see glimmering water within walking distance — or at least some kind of liquid that wasn’t their own sweat. Jordan Tropf, a former Navy cross country runner and current student at the Johns Hopkins University School of Medicine, won the marathon, crossing the line in 2 hours, 29 minutes, 6 seconds, while McDaniel foreign-laguages professor Silvia Baage, 36, of Rockville, won the women’s race in 2:58:36. But runners almost universally hailed the new finish as the highlight of the course. “The feel when you turn this corner onto Pratt Street,” Tropf, 25, said, “is just unbelievable.” The 17th annual Baltimore Running Festival began Saturday at 7 a.m. with the 5K.  I tell you, this finish line, you can't beat. You just can't beat it. — Remus Medley, of Baltimore This was Tropf’s first Baltimore Running Festival. He didn’t know what he’d been missing in the 16 years prior. Much of the course remained unchanged Saturday — runners still zipped by the Maryland Zoo in Baltimore, looped around Lake Montebello, crossed the Howard Street Bridge — but the rebooted ending