After 1 months with 17950 I can put few words.
My setup is Stock dp + stock kat + 17950 VB + Clubsport S (muffler).
When you travel below 70mph and ride without "boost" it's OK. Nice sound, little bass from exhaust but.... if you use even press a little bit pedal (gas) or you ride between 2200-3300 RPM and use gas to ride faster (even small boost 3-5psi) exhaust is very loud. The same if you go to highway and cross 80mph it's to loud and you hear only bothersome sound. There is almost no drone but the volume is not for daily use out of the city.
Theres only two ways to explain your experience.
A: Part of the exhaust is touching under the car, making a ton of interior noise as a result.
B: You have an extremely low noise tolerance, because a CSS muffler used even without the 17950 is mild in the spectrum of available options for these cars (it is an OEM part that comes from the factory ROW, and those cars have one less cat and therefore are notably louder).
Either way your results are not typical by and stretch of the term. Not posting this to put you down in any way, just avoiding later confusion by readers of this thread.