The sound isn't bad, but no S65 for sure.
IMO The 1M sounds awesome with an Akrapovic exhaust, this engine should be no different.
Funny thing is, the so called M purists hate on the inline-6 sound that has been a long standing trademark of the M division........ The first ever real M engine was the M88/1 and it was an inline-6, and one with a ~7K RPM redline at that. For Group 5 racing they turbocharged the M88 and called it the M88/2........ Depending on how they play out this new engine, they can claim to be doing a throw back to the early M racing engines.
2011 E90 M3 ZCP - Individual Moonstone/Individual Amarone Extended/Individual Piano Black With Inlay:LINK!!!
1994 Euro E36 M3 Sedan - Daytona Violet/Mulberry:LINK!!!