Purchased and installed this STC on my G35 three years ago. Engine pulled and sent to G&N (Griffith, IN) for overhaul and STC incorp. G&N has experience now on doing this mod. The STC instructions are not that straight forward and many phone calls with AeroResearch to get clarifictions. We installed steel cylinders, if I had to do it again, I would go with Nickel cylinders. All new cylinder baffles need to be installed, I think they came with the STC. The 470 cylinders are slightly larger and it is a tight fit on the left side of the engine compartment. We had to purchase all new exhaust system. No fuel line mods req'd. No problem with stock induction system.
Maintenance has been just like a stock engine. Had two problems that both showed up 300 SMOH: 1) premature exhaust valve guide failure on one cylinder; and 2) oil leak on one cylinder to crankcase surface (turned out to be wrong o-ring installed by G&N).
Performance is great. You can run max RPM, max throttle longer on climb out (5 min instead of 1 min). Though not officially sanctioned in STC, you can run the engine at higher RPM/MP (>23 squared) if you so wish. ARS did this as part of their development program so the engine is good for it, it is just that they did not take the time/money to get the airframe approved for higher RPM/MP, so original TC restrictions apply. Of course you get resultant higher fuel burn (nothing is for free). I consistently see 1000 fpm climb with 2 people on board, even on warm day. 350F or less CHTs at cruise but keep eye on things during climb, in fact I find that I get 500 fpm at 110-120kts, and that helps keep the CHTs down.
All in all, I am happy with the mod. Not cheap but I believe I have a better engine for it. I have pictures of the installation which I can share if you are interested.