First Audi need advice

Hi everyone, 

so have just acquired a slightly modded Audi A4 sline b170 2.0 tdi. It’s running stage 2 map 220bhp 440 torque atm with the mods on it. I was wondering what’s the max bhp it can take without head and rod work etc and how achievable and cost with list of parts to get to the 300bhp mark on them ? 
 

sorry if been asked million a times before like said I have always had jap cars before this venture. 
 

thank you to everyone in advance for any input on the subject :) 

rob