Hello there

I'm new to forums so be gentl

I've just bought a mk4 gti 20v
I bought with a remap already done and a k&n panel filter which is producing just under 200bhp, I've read a few posts about tuning them and the agu engine seems robe more tunable? Not sure wat mine is? It's a w reg.
In the next couple weeks I'm going to buy a fmic of eBay 200 quid, and a sportex back box and race tube along with a decat :-/ ? A walbro fuel pump, was wondering if and wat injectors to get and would I need to upgrade turbo? Been looking at k04-001? What sort of bop wud this get me?
If I was to do any of this would I need to remap ecu again?
Cheers