@ the OP
Without the intake your always going to limit the power available with the std K04 turbo. Adding the HPFP and getting a stage 2+ map will release more midrange although your top end will still be choked by the stock airbox. Id expect 320-330Hp with stage 2+ on the stock intake.
The other option i think as keith and carl have said is to go for a bigger turbo. That will give you the extra power, but of course its still going to be running no where near its potential if your still running the stock airbox. Have you considered an enclosed intake? They are alot quieter than the open filters.
If you dont want noise, id steer clear of the evoms, ITG maxogen, neuspeeds, BSH etc
Your the same as me tbh, i dont want to much noise. im running just a DP and an enclosed filter intake on my car and its marginally louder than stock.