I replaced my plugs last year and it made quite a difference. They were worn pretty bad and the tips were dissapearing. It made a huge power/throttle response/acceleration difference with the new plugs in it. I don't remember which plugs i got. I think they were bosch plats. They seem to work fine. I also like the copper plugs. They are usually the best performing plugs all around. In some cases however (my VW GLI) it will chew through the coppers in about 3500 miles. I have to go with irids which is what the car comes with.