Wat makes one plug better than another?of course this depends on what is important to u..
if ur looking for max performance, there are certain plugs that are designed to minimize misfires/ max the combustion of the air.fuel mixture.
if ur looking for maximum service intervals..there are plugs that r designed for the limited gap erosion.allowing then to function 2 to 5 times longer than conventional plugs.
HOT OR COLD?
one of the most important considerations when choosing a replacement plug is being sure that the correct heat range is chosen!if the replacement plug that is chosen is too cold..fouling occurs.this leads to misfiring and poor performance..increased emissions and FC decreases..
if the replacement plug has a heat range that is too hot..the results are WORSE!the plugs can become so hot that its temperature ignites the fuel BEFORE the spark ever has a chance to fire,this causes pre-ignition.and u all know this sucks.
to determine if ur plug is of the correct heat range for ur level of mods..and driving styles..u can inspect ur plugs after a pass on the dyno...or a few miles of driving on the street..if the firing end of the plugs is covered in black soot,the plug u have chosen is too COLD.
if the firing end has a tan,light brown or light grey apprearence on the insulator and electrode..u have chose the correct heat range.
but IF the electrodes appear melted or rounded is apparent on the insulator..the heat range u chose is TOO HOT.
basically this is wat u shud know when buying ur plugs.not the increase of hp it would give.