Although from the pics all the other cylinders look decent right?
Best have that 1 injector flowed and tested,Also if that was cylinder number 1 on a rail fed on the stock side,It may be leaned out,Next time out,Pull a few plugs after a good run and double check them
Up until this all the plugs have been fine, I guess I'll have to step up the fuel rails and injectors this time around.