I've always strongly favored (and recommended to everyone), Stevie Marshall's Ferrari V-10 Sound (including shifting backfire sounds) v4. for most F1 seasons (the engine pitch changes with the engine rpm, so it's progressively higher pitched for recent F1 seasons and lower pitched for older F1 seasons, providing that you adust the engine rpm with the GP3 Physics Editor).
For CART seasons, Klaus' (who you probably know from his GPL track graphics) CART sounds are the only ones that I can recommend, as not only do they sound the most realistic, but they are the only bug-free GP3 CART sounds that I have ever found.
For mid-1990's F1 seasons, when Renault was the dominant engine in F1, I like the Renault sound found on this website.
All of the above sounds can probably be found in the GP3 downloads section of this website.
For the latter 1980's through the early 1990's when Honda was the dominant powerplant in F1, I've found that the GP2 Honda sound, that can be downloaded from www.GrandPrix2.com, works and sounds splendid in GP3, very much like the Honda engine sounds in various Senna onboard videos from those years.
Edited 3 time(s). Last edit at 01/31/2005 01:23PM by JackiMatra.