I've updated my Well MB01 and thought I'd share in case any one wanted to do the same.
I bought the gun from Taiwanguns.pl for £78 with Piston upgrade, scope and silencer.
I bought grease and Barrel Spacer from airsoft sniper parts UK, and metal Trigger box from ebay from China.
The easiest job was replacing the piston and spring guide, lots of YouTube videos for that, I cut down the spring by 2 coils as I wanted this to be roughly under 450 fps, as lots of sites stated this was shooting in the range of 460-470 fps. I'm not able to tell what the fps differences are as I don't have a chronograph as yet. I still have the 500 fps spring that came with the upgrade kit just in case I cut it too short.
Next part was removing the barrel to put the spacers I bought from airsoft sniper parts, again youtube has lots of vids on this and I've attached a pic of what it looked like. The foam spacers where already attached to the barrel and I used them again as they were a good fit, but did move position when I fitted the barrel in so getting 4 spacers would of done a better job than 2. I have heard from reviews that the spacers add a small amount to accuracy and as it was only £9 I thought I'd give it ago.
Last was the trigger box, I had heard of the MB01 trigger box spitting and it was also recommended if you used a higher spring it was recommended to use one. So I spent £22.50 from ebay for this. It added some extra weight but I hope this will last ages.
I didn't bother with upgrading the barrel, I've seen reviews for the tight bores and people prefer wider bores for sniping, so I left that for another time when I want to play with the hob up.
Pic of the trigger boxes, metal box on the left.