I've had the bosh plus 4. Piece of crap burnt Chevy dealer pulled the plug when I had issues with the mass air Guy told me just buy the ac delco plug any plug better for the money of iridium

 

NGK TR55 gapped at .055". Replace every 20k miles.

 

+1 for a N/A engine

 

^^^ I've read the same

 

Stock AC Delco's Gapped to .040

They will go 100,000 plus miles.

 

The only problem with the Iridium plugs is that older engines will foul them unlike Copper plugs which don't suffer from oiling as much.

 

I've tried everything on the market and I can safely say that the best plugs are always the stock ones.

 

I have ran the stock acdelco plugs in my 6.0 with both .055 and .040. I am currently running them at .040 when I changed the plugs and tried the .040 gap it seemed to run a little smoother but also kinda feels a little weaker, not sure if its just me or if I lost a little torque.

 

Coming from multiple lsx cars.... they love ngk plugs. Thats all I've ever really used.

 

STOCK plugs. 55's Still run them, with boost.