Army Glock R17 Upgrade Advice

[Hellfish]

I have one of these and am looking to upgrade ...

So far I have purchased some high flow valves for the magazines, and will probably end up replacing the seals with some of better quality or using some seal sealant to prevent leaks, but I'm primarily after advice regarding the pistol internals.

I have never attempted pistol upgrades so any advice on components and brands is much appreciated.