The stock na pump is pretty puny, I wouldn't try to get much HP out of it.... especially when you can get a Walbro for around $100 and never have a fuel worry again. The lines are fine up to around 500hp.
Slasher, I made my 602rwhp pull with a single Walbro pump... no need to have that stocker in there too. Frank is right, I have a single -6an line for fuel feed and I use the stock return line... and you really can't hear the pump much... maybe slightly if you stand outside behind the car at idle.
I'm running on the stock FP ecu/wiring. I normally run a econd Walbro which I have running on it's own wiring/fuse/relay, but I had a bad relay so I just ran one pump at that dyno session. 500-550rwhp is all I would push with the walbro, allowing some factor of safety. I pushed the shit out of it at the dyno.