12mm fuel line 306 hdi

[boggs]

Due to being stupidly low I ripped off my fuel lines on my 306 hdi I have now fitted sheet metal to protect this issue. I want to replace the full feed line to 12mm piping how many metres would I need? Has anyone ever done this mod to an hdi? I know plenty have done it to xud engines but havnt heard much about hdis. Its also going to feed my R70 pump. Will there be any benefits or point I'm upgrading the return line if so I would be thinking 10mm. 

Thanks I'm advance