07 Is350 w/130k miles bought used 10k miles ago. Just replaced the spark plugs and 3 were loose. The 1st was so loose that I accidentally put my 10mm socket down the hole and it grabbed the top of the plug and pulled it out. Replaced all with the denso plugs $10ea. Might make the car run a little better. Pretty easy job, took about 1 hr. Im thinking these have never been changed as they looked a little hot (white).

 

Damn that couldve been bad. Also sounds like youre gonna get some performance increase