Citation VII Interior Sound Levels ??

[P3-Adub]

We operate a 1995 Citation VII that seems to be very loud inside. Above 200kts indicated there is excessive skin screech and fan noise. I know that later VIIs came out with a secondary door seal however I was wondering if anyone has installed any other soundproofing package in the VII or the III and what decibel reductions have you attained ? We are considering getting a sound survey to see where the majority of the noise is coming from. With a secondary door seal and added soundproofing, we will effectively lose one passenger in payload ability. A welcome trade off if significant results are attainable.

Thanks in advance for any input.