The thermal coating is the cats azz and if you do the SC inlet snout, the Y-pipe, the IC and the CAI, it will yield significantly cooler intake air temps as air getting into the supercharger is cooler and more heat from the engine makes it's way into the intercooler and Y-pipe and in turn translates into a denser air charge and more power as cooler air has more oxygen molecules per a given volume than warmer air.

As they are now with the silver teflon coating, price is $650 shipped so you're saving about $200. Same goes for having them thermal coated at $850 shipped. Going with a new set from Rob or my used ones really won't make a difference performance-wise and you'll be very happy with either set you get but mine are itchin' to get back on an engine though and feel useful again. LOL