X2 or you can run it through the door then splice the black groommit that holds all the door wires and then run it through there. anyway will work fine.I gots an 00 impala and there is a way thru @ the bottom by the passengers seat. You gotta take off the part under the glove box. I think its the same in the 03
ive got an 05 and id like some pics of that if you got emthere is a rubber grommet on the passenger side under dash thats where I ran my power in my 05impala...Can get pics if you need them..