Originally Posted by sonoronos

Approximately:

440bhp @ 1 bar boost (14.7 psi)
660bhp @ 2 bar boost (29.4 psi)
880bhp @ 3 bar boost (44.1 psi)
1100bhp @ 4 bar boost (58.8 psi)

Now, if you were to modify the N/A hp to 200whp using top-end work, then you could theoretically make:

500bhp @ 1 bar boost
750bhp @ 2 bar boost
1000bhp @ 3 bar boost
1250bhp @ 4 bar boost