There is always a trade-off in your power band depending on the turbine you chose. If you are looking to get large bhp figures out of a tiny 1300cc engine, you will acheive that with a larger turbo like that td05. The trade-off is you lose pretty much all, and I mean ALL of your lower end power and torque. Add to that the fact that your power delivery is no longer linear, insted you get a massive surge high in the rpm range, just before your shift point, severely limiting your usable power. This is perfect for drag racers, but totally inpratical for everyday driving senarios like traffic, corner entry/exits on twisty roads etc.
The other end of the spectrum is lower top bhp figures but massive low-mid range power, torque and response smaller, quicker spooling turbines can give. The car becomes a weapon in all situations except long straight roads where the top end power of larger turbines would prevail. Find a compromise between the two like a td04l 13g, or a well built ct9 hybrid and you can have the best of both worlds. I have seen response & agility devastate brute power time and time again. Just my 2cents.