i'm trying to figure what plugs to run in my car.....i work at a parts store and can get pretty good deals...i have a 350 running about 10.3:1 compression with cam headers double bump heads milled to 60cc with dished pistons and the works and am having trouble finding plugs to use...i found normal ac's burn out quickly(cr43ts), i ran NGK's before but cant remember the number and they ran good UR4 seems to ring a bell i think u looked plugs for a 350 outta a vette...i tried the acdelco rapid fires they were a little pricey so i thought what the hey...nothing but problems!!! will work great for a while then all the sudden miss miss miss...spray the headers and find which one is missing clean it and its good again for a while...now i read people saying run projected and some say non projected tip any reasons why...pros & cons? whats a stock sbc plug non projected?? not sure.....i have a msd coil and module as well so good spark...so if anyone has any recomendations or part numbers it would help alot...i was looking a NGK iridiums but thats $80 plug change at my price...