[Closed] Central heating plumbing question

We're doing a bit of remodelling and a couple of radiators need to be moved. I'm draining the system and capping at the manifold, but it's all 8mm (5/16"? - it's an old house and old system) tubing. Would there be any benefit to replacing this with larger diameter tubing when the rads are reinstated or should I just stick with what's already there? The rest of the house is 8mm as well. I understand there is an ideal flow requirement for central heating systems but not sure exactly how to calculate this.