Weird engine rattle under 2000RPM

[scirocco.0345]

Hi Guys i'm new on this forum and would like to introduce myself. I'm a proud scirocco owner from The Netherlands. Under the bonnet there is a 1.4 TSI (twincharger) engine. I did some mods to it: Pro Ram open air intake for 2.0 TS(F)I. Aftermarket blow off valve. R32 Look exhaust without silencer. Also the car has an stage 1 tune on it.

But now i've got a problem. The engine had a revision about 2000 miles ago. And now there is an really loud engine rattle when driving and revving under 2000 RPM. I have got no lights on the dash and there are no codes popping up when reading it with an OBD2. Things that i've already changed beside the engine revision.

- N80
- Fuel filter
- HPFP
- Camshaft adjuster
- new turbo
- PCV valve
- And used some different types of oil like 5w40 instead of 5w30

The rattle is most hearable in the cilinder 1 and 2 area (timing chain side of the engine). Diagnosed with the old screwdriver to ear method. But now i'm stuck and i dont know what to do. Please help me out i'm thinking it could be the waterpump as it wasnt replaced with the engine revision. the timing chain has been done btw.