Unsolved How would I make the engine louder when it hits specific RPM?

I want to make a "Vtec" covet. Ive got the Vtec long block all done but I cant seem to use the same code base for the engine volume.
"soundConfig": {
"mainGain": [
[ "rpm", "mainGain" ],
[ 0, 1 ],
[ 1000, -8.5 ],
[ 2500, -8.5 ],
[ 4000, -8.5 ],
[ 5000, -8.5 ],
[ 5999, -8.5 ],
[ 6000, -2 ],
[ 7000, -2 ],
[ 7500, -2 ],
[ 8000, -2 ],
[ 8500, -2 ],
[ 9000, -2 ],
[ 10000, -2 ]
]
},

this is what I have. As you can see the "vtec" kicks in at 6000 RPM. I know that Vtec mods exist but they dont use the default sounds and the default in game sounds sound much better in my oppinion. Also I prefer to make things my self and I also like to learn new stuff.

thanks to anyone that can help me.