I'm just thinking out loud When going for big power people will normally fit a inline pump, maybe a 4 bar fuel pressure regulator and/or bigger injectors but thats ok unto a limit i'm sure but what are the limits of the standard fuel rails, fuel lines and a inline pump as a guide line. I was thinking of changing mine in the future as Bill said i will be trying to push lots of fuel though a 6mm fuel line if i up my line pressure to get over 540bhp and would need to check the pressure at the rail. If i was to fit a swirl pot feed by the S3 pump then use the bigger fuel line from that to the 2nd pump and bigger fuel line to the rail with a modified inlet on the rail or aftermarket one would that be safe and i take it the 6 mm return is ok i assume? now if i change my 870cc to 1000cc would the standard stuff still be ok as i wouldn't need to run higher fuel pressure? I know some will say why fit a swirl pot, well it could work out cheaper to do it that way as 1000cc+ aren't cheap. As said i'm just thinking out loud?