Octavia mk1 turning and info

Hi I have a standard Octavia 2003 1.9 tdi ALH, but she's very flat, I have cleaned every thing out ie intake, vacuum pipes, intercooler, egr, av had her looked over by a couple of garages and there's nothing mechanically rong, so I want to tune her, I have been told to get the t4 150bhp injectors, or the Volvo v70 2.5 tdi?? But there's loads of different part numbers for injectors that look the same,

So far I have

Pipercross induction kit

Egr blank

Decat pipe

I know I need a lot more!!!

Am looking to buy these injectors 074130201Q but I can't find much info on them so I don't know if there right