i'll be doing the lt1 intake swap in a couple weeks but i have the electric lg4 pump in my tank still. i'll be putting an inline pump on. will having the in tank pump restrict flow or anything? currently i'm using a mechanical pump and it seems to be fine but it's only like 6psi, not 40-50 like it will be.

 

My understanding is it is better to put the higher output intank pump in. That external pump will have to suck fuel through the old pump, sock etc. Plus external pumps are louder than their intank counterparts.
http://www.autoperformanceengineering.com/
They have the cheapest prices on Walbro pumps.

 

Efi is finicky to pressure and volume; better to swap it. The whole distribution system works on pressure, so you could end up doning some damage being carb lean...

Run an adjustable fp regulator too...just a thought. More tuning without playing with the ECU.

 

any other input? right now i think i'll replace the intank pump. at the autoperformance site, they have three different pumps, a 190liter/hr, a 255liter/hr and a high pressure 255liter/hr. which do i want?

 

The 255lph regular pressure model is more than enough for most applications.