amp's power wire outside the cabin?

My specs... 2004 Chevy Silverado Extended Cab 4x4 JL 250/1 JL 300/4 I am planning an install in my truck. I am planning on putting the above amps behind the back seat on the rear firewall. As the title suggests I am considering routing the amps power wire and ground under the cab. I will enter the cab through the floor using grommets to protect the wires. While under the cab I will run the wires through conduit to protect them from any kind of nasties that may want to come in contact with them. Everything will be tied up & secured inside the C channel frame with the rest of the vehicles factory wiring. I have read people doing it this way. I have also read people saying absolutely do not do it this way. I have never heard/read why? Can anyone see a problem with this? Does anyone have any negative/positive experience with doing the wiring this way?

No issues with doing this provided the wires are properly secured  / protected from debris that may come up. Most if not all wire is waterproof and temperature extreme resistant. Again make sure that the wire is properly protected, I would run the wire inside of an armored cable, found at some commercial electrical stores and maybe the odd Home Depot. Top Secret, I can tell you but then my wife will kill me.

I run my power cable underneath the truck, but I have it bolted to the frame, so it's not going anywhere. I also made sure to keep it from all moving parts. Paul

I've done a few cars like that also. No problems from any of them.  '85 Toy

yeah. it's ok. just pay attention to detail.

I've seen some installs that run the wire inside of armored conduit / greenfield. It too can be found at Home Depot or Lowes. The nice thing about that stuff is that you can use the same pass through connectors that the electricians use to wire into a junction box. Nice and clean.... WTB: Black Leather Acura GSR seats

I assume this is what you are talking about. That is my plan so far. I will attach it to the frame rail inside the channel with metal d clips. Thanks everyone for your information.

 i own a ford transit van with 2x 9515DD  subs and 2 x1800watt amps  i have had to use o guage cable. i had to run it under the van has long as it's safe it's okbass it to bits baby