This is actually easy. Go into the customization menu in the garage and play around with tone, timbre, overrun, and pipe resonance to try to find the perfect balance for them. NOTE: .All of these sliders modify the sound in slightly different ways on each car and at different performance levels. Once you have customized your sound, take your car out with this setup and race. If you win with your new customized sound setup the achievement will unlock AFTER the race. It's that easy. Move a slider, race and win and poof gamerscore. Happy hunting.
QuasarWaerter says that you need to win a race at night to unlock this achievement. To be frank, I cannot remember if I won during the day or night so it does not hurt to follow QuasarWaerter's advice.