I haven’t used the Euro L or Castrol yet; I have about 50qts of the Euro 0W-40 (not the SRT version) that I’ll probably use, with a 5-6k bogey. The oil in that UOA was Ravenol DXG, I used a bunch of free Amazon gift cards. My last fill of DXG is in the sump right now for what was on the shelf.
As far as tunes go, I don’t have any 1st Gen experience, but 5 Star is solid with good tech support, and I know Brew City Boost has had a lot of press. Just realize that the magic of the 2nd Gen is the port injectors; there is so much inherent fueling capability when running ethanol mixes that’s missing on 1G. Heck, the 2.7 can run a straight E85 tune on factory equipment, where the 3.5 is limited to about E30 on the factory in-tank and HP pumps. If I want to go to E50, it takes an in-tank pump upgrade, and E85 requires HP pump as well.
However, going from E30 to E85 would pick up well over 100HP, but cost nearly $2k in fuel pumps. For now, I’m content with roughly 500whp. I’ve got the AMS inlet tubes ready to go, and will likely add the CVF Titan 2 intercooler, turbo adapters, and a mid-pipe as money allows. Really, you should seriously consider an intercooler upgrade on 1G, because while not a big HP producer, it will definitely help keep the engine happier in the heat and is never a bad upgrade on any boosted engine.