I have the sprint re and was wondering if I can use the stock ground that's already in the terminal. So what I was planing to do is just add the new 12v power to the stock fuel pump terminal and just plug it in.

 

yep, before you really start trying to make big power you should probably check the pump voltage, but it should be totally fine

 

The stock connectors at the fuel pump are pretty craptastic. I like to bypass the whole mess. Add your own 12g feed from the battery, through a fuse and relay, directly to the pump. A Deutsch DTP or similar will ensure minimal voltage drop. Use the Haltech output to switch the new relay on/off.

 

That's what i'm doing but I was just using the stock connector. So your saying that should use a different connector. Would this connector work fine?
http://www.ebay.com/itm/PER-047-12-Weather-Pack-Connector-4-Pin-Kit-12-Gauge-Weathertight-Sealed-Seal-/230795606085?hash=item35bc7d7845&vxp=mtr
Also on another note, is the only thing I need from the old harness is the wiper harness? It's an 88T2 harness.

 

correct. the wiper harness

 

Weatherpack will work, though I'm not a fan.