Review on 🔥 NGK 4291 V-Power Spark Plug - ZFR6F-11, 4 Pack: Top-Quality Ignition Upgrade for Optimal Engine Performance by David Thomley

I bought 4 of these for my 2004 MazdaSpeed Miata (Mx-5). They fit perfectly. There are several enthusiast websites/forums that recommend using them in turbocharged cars due to the deeper seat - they are located deeper in the engine where the spark can be more effective, especially compared to regular length spark plugs. I'm not 100% sure what the science is behind this, nor am I sure how they compare to iridium, platinum, etc. I pulled my old spark plugs when I did a 60k service and they looked perfectly normal (No Oil, No Oil). soiling, no blackening, etc.). I decided to switch anyway, since I've already paid for new ones - quite possible since they're only $2-3 apiece. Although my old candles looked fine, these seem like a great upgrade. Maybe it's a deeper plug, maybe because they're new, maybe it's a placebo, who knows. But the engine seems smoother and feels like it's purring compared to what it was before. Be sure to purchase a spark plug gapping tool and install it according to the specifications in your vehicle's owner's manual. They're not correctly installed by default for every machine, so be sure to check them out.