I didn’t get hung up one Stage 1 or 2 as that can be a rabbit warren. I went to Allisport who use maps from ‘TD5 inside’, they baselined my vehicle then asked me what I wanted - so with no other mods/money spent it was tuned up to something like 140bhp but the torque curve was improved massively along with response. About £300 from memory and worth it

I will eventually take mine to 710 Engineering in Edinburgh, they are linked with Alive tuning. Going to strip out and sell my AC and then but in an updated IC, put a D cat on then get it remapped. Might take a while but I am in no hurry