Good tips., I replaced the front one without any difficulty in about ten minutes but the three in back was some ting. Poor design by the Lexus engineers. I guess, they do not have to work themselves and expect all consumers like do-it-yourself type (us folks) to use dealership for all service needs. I removed PVC and its hose as well as cruise control bracket assembly. I used two three inched extension for the driverside and center one. My small hands worked in tight space very well. the one on passenger side was tight to pull as well to insert back in hole. too close to fire wall. I managed to use one three inch extension with a universal and was able to install all three in one and half hour. I used Bosch Platinum 2 Part number #4301 spark plugs instead of the one recommended above but continued misfire after 500 miles. Then I replaced NGK iridium plugs as recommended. I have driven for over 2000 miles and no more misfire.