OK Boys and girls I'm going to throw this out here and see who has any real world feedback for me.

It is sparkplug changing time. I am contemplating the virtues of going up to a high performance plug. i.e. Splitfire, Bosch Platinum + etc.

So my questions are who has any experience with an aftermarket so called hihg performance plug.

I am a bit familiar with the Splitfire in a conventional electronic ignition. But the newer HEI ignitions will pretty much put a spark through a nail if it needs to. I see them burn the electrode down to a tiny nub and they keep sparking. So that being said, who has used/seen/recommended a high performance sparkplug.

I can read all the hype and gaurantees in the world. Means nothing to me. I want to hear from actual use. They all say theirs is the best thing since internal combustion. But in reality the ignition systems are pretty darn good these days.

Do they improve A) performance B) mileage C) chmaber cleanleness. O.K. C) is going to be an optional answer as I doubt anyone has had to actually prove that one yet.

I am going to cross post this in Engines as well as other aftermarket if I can figure out how to do that?....

 

TallTommG,
Your original plugs should be good for 100,000 miles. If you are not there, I wouldn't recommend replacing them just yet.
Once you decide to replace them, I highly suggest staying with the Motorcraft plugs and replacing the wires at the same time (also Motorcraft).
I used Bosch Platinum4 at 50,000 and turned out to be a waste of money and time. I did not notice any improvement in performance or otherwise. Then at about 80,000 it started to missfire. After several re-settings on the computer, I changed back to original plugs. Haven't had any problems since.
By the way, a dealer can charge up to $650 for replacing plugs & wires, which I think is obscene. Doing the job yourself (plugs and wires) will run approx. $140 in parts, 4 hours of your time and lots of bruised knuckles.

 

I haven't replaced mine yet, but I'm looking at the Denso Iridium or NGK Iridium plugs. Many of the Lightning posters use the Denso's. I have not seen any press on the NGK Iridiums though. The Denso's will run anywhere from 7-13 bucks per plug.

I have heard that the part number for the Denso's is IT16 (their hottest plug) that applies to all later model 4.6's & 5.4's. However, some of the guys are running the IT20 and IT22, which are colder, respectively.