Steve Ficacci warned me about this with a story about a prostock dyno session where they tried running an old set of rusty headers ruining the engine.
I usually scrub my headers with a brush and a bucket of soapy water then rinse with a hose. Use a long tapered brush meant for cleaning under refrigerator or heating unit. It looks like and anteater. Lot's of junk will be in the bucket.
Fog your engine good when done for the weekend and plug collectors with rags. Replace your good race plugs with a set you only use for fogging and warm up after sitting a few weeks.
__________________
Frank Ferrucci I/SA 1271 "Be Thankful for the Gifts You are Given"