Spark plug Bosch or OEM Subaru

As for your plugs, bosch is deff the recommended brand, but just about any high quality plug designed for your engine will work fine. (im currently running platinum in mine, and their fine, but lots of people have reported idel issues with them.) The motor was designed around a copper plug, so thats what it should run on best. so bosch copper is deff the way to go.

newer Bosch plugs, cap, rotor (maybe 15k ago)

Recently replaced original spark plug wire set w/new Bosch; wire set, distributor cap, rotor, O2 sensor and Platinum spark plugs

I think that the recommended plug (and original equipment) is probably a Bosch Silver plug, and that is what I would probably stick to if I were you.

the car seems to run really good at the .028 with the bosch plugs

I've been researching spark plugs and i believe the oem's in Phaeton are Platinum. I am certainly going to verify that and will change mine to Iridium's. For the purpose of better power, performance, and fuel mileage.

Changed spark plugs, wires, cap/rotor with Bosch bits (w7dtc not those crappy +4s)

Every time I fill up I check my mileage, I could never get great MPG from the FR8DS, but the coppers were way better MPG wise. Throttle response was less as well. The Silbers always looked more sooty during inspections than the coppers. The silver plug will last longer.

Do not use the Silber plugs. Mileage and performance suffers.

I've had nothing but trouble with the Bosch plugs, from their cheap-o line to their IR Fusion line...