Engine audio bug

when revved too quickly the engine sound stutters and cuts out, sounds very ugly. i tried turning graphics settings to minimum, no improvement.
i have i5 3450 @ 3.1ghz, 8gb 1600 ram, SSD + 2x 2tb Sata, AMD 7870 2gb.
this set up really should not struggle at all, it does not have issues on full settings, and on low settings the audio bug does not improve.
this is using a 6L V8 32valve DOHC Direct Injected - 540hp 610nm 59 responsiveness.
i have noticed this bug with other motors also
i have i5 3450 @ 3.1ghz, 8gb 1600 ram, SSD + 2x 2tb Sata, AMD 7870 2gb.
this set up really should not struggle at all, it does not have issues on full settings, and on low settings the audio bug does not improve.
this is using a 6L V8 32valve DOHC Direct Injected - 540hp 610nm 59 responsiveness.
i have noticed this bug with other motors also