Spark plug NGK or Denso

I swapped out to APR coil packs and NGK-R7437-9 plugs at the recommendation of APR after going stage 1. No issues after about 8K miles.

NGK has NEVER let me down in any of their products. I use them in my American and Japanese cars, trucks, motorcycles, lawn mowers, leaf blowers, weed heaters, and chain saws.

I've been running the 2.0t/r8 coil packs for a few years now and haven't had issues with them.

NGK actually makes the original plugs for the mk3 focus (because the engine is based on a Mazda L series) so if you're doing plugs for a focus using NGK will be just as good if not better than the "oem" brand

As long as you use the right type and gapped correctly, then you are fine. NGK, Autolite, Motorcraft, bosch, all are fine.

I just replaced mine, at 80k, with Denso PLatinums. The same brand as the stock plugs.

I have been running them for 50,000 miles with is20 then is38 setup. Work perfect.

I just ordered new spark plugs and an oil filter as well.

For a stock 4.3 you won’t see any performance difference regardless of what you put in there. Cheap copper plugs will work great but your going to be replacing them every 25-30,000 miles, iridium will probably last as long as the rest of the vehicle.

Subaru's like NGK (OEM) spark plugs and O2 sensors, respectively. They run poorly and will even throw codes if other parts are used.