The TDI is direct mechanical injection but is electronically controlled. (common rail like PD engines have electronic injectors)
Sadly the only way to get decent power is a remap, however a remap does make an impressive diffrence!
You might be able to fiddle with the boost controller but i find if you bleed air off it will throw up a control diffrence fault and go into limp mode on the dual carriage way, unplugging the boost valve will put it into a constant limp mode.