When I did mine the pre-chambers looked dirty, I sprayed them with a little card cleaner, but didn't want to go crazy. I don't know of a good way to clean them.

howardjnl I just did mine and the car runs great! It idles smoother than a diesel should! Just give Phil a call he will give you a good price. You will also want the heat shields, and new drip lines. The old ones will be rotten if their original. You also need to torque them to the right spec, I think it is 100ft pounds but am not sure, this is important to set the heat shields.

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2006 CL500
2009 C300 4matic
1969 280SE
2023 Ram 1500
2007 Tiara 3200