Is there any way to clear the carbon inside the exhaust pipe?

Answer 1

Floor it and run it out hard. Hydrocarbon fuel makes black carbon inside the pipes and cat converter adds sulfuric acid to that and water. For car shows i use carburetor cleaner spray and a rag to clean the last four inches inside the tail pipe tips... It has not made me any more points. The over all car appearance is what takes home best of show and first and second places

Answer 2

Run some RXP through the engine.