I just ordered my six gun tuner with speedloader for my 2003 lb7 duramax and i already have an aftermarket pyrometer gauge. Do i have to drill another hole for the banks one or can i just tap into the exsisting one??

You can't "share" pyrometer probes, the gauge will need it's own and the Banks will need its own. :)

I just ordered my six gun tuner with speedloader for my 2003 lb7 duramax and i already have an aftermarket pyrometer gauge. Do i have to drill another hole for the banks one or can i just tap into the exsisting one??

You'll have to tap another if you want to keep using your existing pyro gauge, since the Six-Gun's probe plugs directly into the module.

ok, i installed the six gun tuner with speedloader and im getting codes off of the tuner. One code is an EGT Problem and it tells me to check the wire and thermocouple and they appear to be fine. Then the rest of the codes are wiring harness codes. I took the banks harness out and started comparing the connectors on the factory harness to the GM harness, i noticed on the banks harness the Male connector the plugs into the bottom port in the engine compartment has an extra prong that the stock harness doesnt. Is that a different harness, i bought the kit for a 2001-2004 LB7 which i have an 2004 LB7.