ok guys i know how to install stereo **** i used 2 do it for a living and i know good brands and all that all i am wondering is i have a 2002 Lancer oz rally edition,there is already an upgraded kenwood deck that was in there when i bought this car. I am looking into putting 1 orion 12 in the truck just to add a little bit of bass, are there any problems im going to run into when im runnin the wires just tryin to see if any1 has done it already so i know wat 2 expect i am goin 2 run the wires driver side under the carpet and under the back seat to the back

You shouldn't have any problems, just make sure to run the power wire down one side, and the rca's down the other.

you said orion. are you talking about the HCCA. if you are then GREAT choice. the HCCA is a great sub.
but what gets me is you did this for a living but you asking if there is anything wierd. if you were an installer it shouldn't matter what there is you should be able to handle it. but w/e it doesn't matter.

get a HCCA please and post pics

i havent done any lancers and some trucks and cars are just tricky like how they do the trim and stuff like that just little tips i was looking for but sound like it will be just a normal install and yea the hcca i already own them i will post pics when i install it