Don't agree with that. Turbos, exhaust, plumbing, oil lines, beefed up suspension, brakes, rear end assembly, etc etc etc. If you sit down and actually add everything up the headers will likely be the cheapest part.
Most block huggers don't work well (turbo placement) upside down' date=' and you will likely not be able to mount the turbos underneath. Plus, the tubing is too light of a gauge, and will not last long.
Cheap is what it is. If you are going to go through the effort, do it right, or you will never get it right