I just upgraded my coils to BavAuto's high performance coils and replaced the plugs at the same time. I used Bosch 4+ platinum plugs but was very dissatisfied with their performance. I pulled them out and replaced with NGK's Iridium plugs......they are GREAT. 10%+ better MPG, smoother idle, better performance, faster response. First time I've ever seen improvement from a different brand plug.....well worth the extra time to pull everything out to replace. Cost was approx $8 per plug from Advance Auto.
