Bat crap ^^^Im using bosch in my 92 deville an audi head told me bosch is better but i think im going to go to ac delco like recommend on my next tune up because ive noticed less HP with these bosch.
did research and found out it is the oil i used 20w50 im taking it out today. A Old guy told me to use it so i tried it . And its just not for my car. SorryBat crap ^^^
Please stop texting and get into the engine forums for your car - the 4.9 is not as finicky about plugs as the Northstar. BUT, DENSO makes a decent spark plug. So does NGK.