Originally Posted by Alon

- Use a drill to make a pilot hole, don't use the self tapping screw as a drill bit. While I agree that you shouldn't have used those particular screws, using a pilot hole on a self tapping bit is ridiculous. They are made to start themselves.
-The bracket mounted to the truck is sitting on the inside corner, which will wear into the paint and eventually cause it to rust. Totally agree with this.
-Two self tapping screws might be fine for a little while but over time (depending on how many lights you have) may break because of wind resistance and impacts of going off road/potholes etc. They are meant to hold sheet metal, not light bars on a truck They might not break, but they will continue to move with the weight, which will cause the hole they are in to become bigger, making the entire assembly flop around like a rag doll.
-You should have used a grommet to run the wires through instead of just runnign them through the (bad) hole you just drilled that has sharp edges and will cut through the wire. You might have put silicone over the hole, but it should still have a grommet or something to protect the wires. Agreed
-The roof of the cab is very flimsy and I wouldn't be surprised if after time it will start to crack the paint all around the brackets and if you are out on a trail and hit a branch or something, I wouldnt trust the drywall screws or the sheet metal to hold up to much. Agreed
-The "light bar" hangs over the sides of the truck quite a bit, not sure how tall you are but I'd probably smack my head into it walking by, and it just looks odd sticking out so far. Agreed

Yah you got what you wanted, lights on the roof for cheap. In my opinion, it looks horrible and you couldnt pay me to do that to my truck. There are many ways to mount lights on a truck, this is NOT one way I would recommend to any member. A simple flat bracket bolted into your bumper would have been much cheaper, much easier and much nicer.

I agree with everyone else, you will probably get some water leaking in. IT might not happen tomorrow or next week, but with the heat/cold and all the flexing the roof will be doing, the silicone may weaken or let water seep through. Even if its just a tiny bit of water every time it rains.... now you have moisture up there.