That's funny, cuz I was pissed, after I went down there in order to set a plugs for a 69 440 Magnum, came back, and they wouldn't fit! So I pulled an old one, I seen they were Lil. It's a good thing I didn't put the 452's I had in the shop on there, it probably would not have helped ! Was thinking more performance, but now in retrospect, I'm thinking Chrysler engineering, to keep your motor running cool, so it lasts a long time, especially if you're pulling that thing filled with crap up the hill somewhere!