Searched and found both answers as usual. So looking for yes or no and if yes, why?
Is a walbro 400 or 450 lph pump too much for stock lines and/or fpr?
2.4 evo 8 with fp black. Will be finished and ready for tuning soon. Just trying to figure out fuel. Car is a daily. Don't want much over 550. Tuner said that's too much to do safely on a single 255. I asked him his thoughts on the next best option. He stated a dual 255 setup, with one on a pressure switch. As this would be effective, it's not price efficient. Considering you can pick up a 450 for a little over 100 shipped. He said, it would be too much for the stock fpr.
Thoughts. And go.

 

im going the same route, 550 should be achievable without a rewire, people do dual 450's on stock lines, you'll be fine, get a rewire and you can go over 600+ with that single 450

 

A re-wire with an upgraded -6 AN feed line and drilled siphon on the return with a single 450 will be enough for 600whp and maybe more.

Look up Mr Fred's thread on how the upgraded line can overcome resistance and keep fuel pressure reasonable.