You will want the heavy coils for sure with that setup. Also, you want to weld a plate onto the frame mount chop. Leaving it uncapped defeats the purpose of having a boxed frame. My buddy is a good friend of one of the toyota engineers who works near ann arbor. He said you must weld a plate onto the end to maintain the structural integrity of the frame. For your average road driver, it isn't a big deal, but if you go off road you will want that boxed for sure. I'll talk to my buddy for a better explanation of why it is necessary. It also makes it look much better, and isn't a ton of extra work anyhow. But there are indeed benefits to rewelding the ends where you make the cut.