Ferrari Enzo makes a glorious roar, so does the jaguar xj13 with it's visible V12. Almost all the historic racing cars sound amazing but the best in my opinion is the Chapparal 2D. That rolling thunder noise under acceleration is mindblowing. Another engine sound that i'm drawn to is the FALKEN GTR race car '04. The sound of it's RB26DETT bouncing off the rev limiter on downshifts is very nice. Highly unusual for a turbo car to sound good!