Originally Posted by
M.D.
I've ran the stock pump on stage 1a (282 bhp) on my s14a for a good few months with no issues at all. It's not that the stock pump can't deliver the pressure or volume of fuel. It's that by now its done a lot of miles so will be warn and eventually stop delivering the pressure needed.
It's a wear and tear thing for a bit of preventative maintenance.
As much as you "can" run it on a stock pump as I have done before. It's not advisable as one min it may be fine the next the pump will have warn and your fuel pressure will drop and the engine will run lean.
To be honest though I'd put most of this happening down to old wiring as well not necessarily a dead pump. Fitting the higher rated pump can disguise. A wiring issue that should IMO be sorted first.