Flex PVC or rigid plumbing pipe? Sump or canister?
You'll have more resistance on the longer side, but otherwise I'd not worry too much about it. Rules of thumb include shorter's better, as is smoother corners (not 90 elbows) and bigger pipes if/when you can, particularly on longer stretches.
If it's a permanent install (IE you won't need to adjust any time soon) then cut the 7 down to 3, or as short as you can. Otherwise don't worry too much, just try to keep the lines straight/simple & corners smooth.