Spark plug Bosch or NGK

Im tuned and on an E85 mix but using 1 step colder NGK's (#ILZKBR7B8DG) gapped to about 0.022...needed these before I even went MHD though. Once I did most of my maintenance, the car required this for proper spark. Night and day of a difference.

I still put a small dab even though the NGK plugs recommend against it. I change my plugs every 15-20k because I have a tuned Focus ST. I already went through 3 sets of NGKs with no problems doing the small dab

I've had multiple Chevy engines that gave random misfire codes with autolite plugs- then ran fine on ngk.

If you want relatively inexpensive and decent look up whatever NGK plug is correct for your car.

I find the car runs way better on the Rutheniums, and I find that the plug gap doesn’t open itself up over time like it was with 6510s.

I went NGK and noticed a small bump in throttle response, changed mine at 100k Km (60k miles) and they were honestly good to throw back in too, so not like the plugs were burnt or fried!

I’ve been running NGK Ruthenium plugs on my stage 1 GTI for 20k miles. No issues.

I've seen with a digital tachometer a 1,000rpm difference between a laser brand spark plug and the oem ngk spark plug in a chainsaw. So for me it's what the oem uses is what I put back in.

Now that I've done the job, I can't tell if it's just in my head but the car seems to have less power now. It was already a sluggish engine to begin with it but it feels like I need to floor it even more. Also, the gas mileage has dropped from 25 MPG to 22.5 MPG.

after putting the new ones i changed all the spark plugs too, to fit them properly with new wires. but the car runned roughly, so bad..and when mechanic unscrew the new spark plugs to see, they were carbonized black, with just a ride around.