i know questions like this are always asked but ive gone back and forth and cant seem to fine the answer. I have a 1999 454 mpi 310 hp motor thats super charged procharger whats the best plugs to run? I bought the iredium plugs and over all it runs great but at idle it has a slight hesitation and i thanks think its from the plugs maybe not but im going to start there since i didnt have that problem before i changed them. so any guys with super chargers your input would be great thanks also whats a good prop size 1999 donzi 22zx currently running a 25 labbed 4 blade running aprox 78 mph

454mpi jacobs ignition dana headers procharged 5lbs of boost reprogramed ecu larger fuel injectors all work done at arz speed and marine

Like to help,,,, but I cant get past your avatar !!!

Drop to a colder plug ,,, either A/C MR42T, or NGK BR8FS

If AZSM did it ask them. I run MR42t's. (AC).

they no longer have mr42t but they have r42t the only difference is that there non marine thanks

That's what i'm running. I lied about the MR part.

bought the rapid fires lets see how they run !!