Strangely the 600 is much louder than the 750, it is really a badass nasty little bike that spools up nicely. The 750 has more punch per throttle angle, and a good induction noise at speed, but real quiet at idle in comparison. I will eventually do a full write up comparison of the 2 bikes later down the road.Bike is loud and has too much power, lol, so glad I didn't get a 750!