Spark plug Denso or OEM Volkswagen

I changed the spark plugs in my nieces 2.5L VW Jetta because it was idling at 1300rpm. Rock solid idle at 700rpm afterwards. Easy way to save some gas.

Changing the spark plugs, spark plug wires, ignition coil and the coolant temperature sensor fixed the cold start issue.

Denso 3457 (FXE24HR11)

Why? It's the plug recommended in the owner's manual and I have never seen anyone have issues with this plug.

Why are they noticeably better than other equivalent plugs from reputable brands, I honestly don't know as it seems that the differences should be negligible. Plugs are one of the areas where the car is very fussy.

I finally changed out the OG Denso spark plugs on my wife's '10 RX350 at a shameful 415,000 kms. Wasn't idling rough but some low-rpms hesitation. Plugs still basically worked fine, though.

Toyota sounds like great deal if they actually use OEM plug (DENSO iridium). That part alone is \\~$18 each (you need 6).

DENSO , Iridium Long Life, SK20HPR-L11 Spark Plug

I would stick with the specd Denso, leave the coils alone.

I already replaced the spark plugs with the Denso ones I listed though... Is this bad?

I highly recommend avoiding anything other than exactly what is specified in your owners manual, I currently have bad gas mileage because I was too curious to see if the desno two tip would do as good as the other stuff.

Hope you screwed them in with the correct torque, unlike my VW dealer. They started to unscrew themselves and causing instant misfire and rpm drops to 200 and engine shutoff.