So I recently did some logs on my 04 sti (stage 2) and noticed my feedback knock numbers were hitting around -6 on fast WOT pulls. So I desided that I would check if there were anything wrong with my spark plugs. When I got the first one out I noticed they were ngk lfr5aix. So I am wondering if having the "5" series plugs could be causing the problem? Since they are 1 heat range higher than the stock plugs. Also would u recommend running one temp range lower maybe the ngk lfr7aix?