Upgrades or mods Discovery TDi 300?

[Black VXR]

I see there are quite a few modifications available for the TDi 300 engine.

My vehicle is one of the last Discovery One's (1999) and seems to be standard. It is running very well.

Should I consider removing the EGR - what does this do and what are the effects?

Should I consider a Cat removal exhaust down pipe? Again what is this designed to do or help with?

Are there any other modifications I should consider or is it best to leave well alone if it’s all working OK?

Cheers.