I did reduce the gap of the PFR7Bs to 0.025" when I was running DriverMotorsports K04+ tune and it boosted more than 26 psi. I did so due to upper rev stumbling, but for being back to running my GIAC HO K04 tune...0.028" works. PFR7B usually work great with higher boost from turbos and tunes when you do notice the stumbling for having arc disturbance.
It appears you already have a good set of coils, start with plugs, buy good ngk plugs. These engines eat plugs especially once you start throwing boost at them, I’m running one heat range colder than factory in mine right now after smoking a factory spec set but I’m pushing 20psi so your results may vary.
Running the ruthenium plugs. Works good for me FR6AHX-S (94279)
Definitely get NGK’s - the parts store I went with initially gave me other plugs and even with a new DIC the engine was still misfiring without NGK’s
NGK is prob the best sparkplug for performance, Denzo is a cheaper option but there not as good for performance
If you live some where hot, have a tune, or are hard on the car I would do one colder and get the 2309 instead of the stock 7913.
Any correct sized , heat range and gapped NGK plug will work fine but some will need to be changed more often. BKR6EIX for example is a good choice, it is iridium tipped and not expensive.
Always stick with NGK. However, NGK has different lines from copper, to platinum, and iridium. Iridium is more expensive, but will last longer. Given they're a bit of a PITA to replace, I'd go with these. I've run them in my 2004 WRX the last 8 years.
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.
I have replaced many brand new NGK's in newer chryslers after the customer gets them from a parts store. NGK's can and will cause ignition coil secondary circuit codes. Also, on hemi's they will set asd control circuit codes and cause the car to stall.
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