Which is a better plug to use in moderately modified normally aspirated old style head 2008 Mustang GT. The Ford one step colder racing plug or the plug manufactured by Brisk. I have Champion Platinum plugs in the car and they were about $160 for the set from advance and I was not too thrilled with them from the start.
Any suggestions as the car is driven mostly moderately with occasional trips to the red line of the Comp Cams....
Thanks for your help and assistance as I am trying to rid myself of a non-felt random misfire.
I would re-think going to a colder plug (unless of course you're F/I).. there are a few reasons for this.
Plugs have to get hot enough to clean themselves. Typically colder plugs are reserved for high compression and/or boosted applications.. The reasons being are because the cylinder pressures are much higher and ignition temperatures hotter.
The colder range plug works to transfer heat away from the electrode faster thus reducing the likelihood of a hot plug causing pre-ignition.
On the other hand, colder plugs in a lower compression setting (like in your N/A motor) may not get hot enough to burn off the carbon deposits because now they're transferring too much heat away while ignition temperatures are cooler which, in turn, could eventually lead to fouling and..... more misfires.
In your case stick with the OEM heat range.
Now, all that said. I run the Brisk plugs and I like them for a few reasons. The most obvious reason is I have early style heads and the Brisk are a one piece design. Also they have a traditional ground strap vs. the autolite/motorcraft plugs which means you can gap them with a good ole keychain wedge vs. having to buy a special tool.
They're a little spendy for spark plugs but not near as expensive as getting a broken two piece removed by the stealership
You can get the Brink plug in a standard heat range plug too.
Good Luck with it
Also if you know which cylinder is misfiring, try removing the COP from that cylinder and swapping it with a COP from another cylinder. Does the misfire follow the COP to the new cylinder?