I have a wrx with a Sti 2.5L short block using the stock 2.0L heads. Now here is the problem the plugs that i have been using (which are the stock wrx ngks) the ceramic will completly disconnect itself from the metal. so you are able to hold the metal nut and spin the ceramic from where the coil over connects to the plug and the tip that is inside of the combustion camber will also spin. so should i use the sti plug which is longer or stick with a colder wrx plug?