I have meth on my m3 to cool the IAT to prevent heatsoak with the blower, trust me I know how beneficial it is. I also had a 335 with JB4 and procede, and I know exactly how it works. That being said, I would much rather have a custom dynotune flashed into my ECU by Bren then have a piggyback/meth setup by Shiv.
Also, his dyno reads right in line with other dynojets. He uses shootout mode and doesnt skew the results with absurd correction factors.