I just got a pre-owned Lexus RCF in ultra white which had quad exhaust pipes that were somewhat clean on the exterior but very dirty on the interior. And it was really annoying because the car looks really good when clean or a little dirty, but from the back it looked horrible from the back because of the black marks inside the pipes and a blackening blemish on the outside. So I consulted with one of my good friends, who suggested using "All Wheel Cleaner" from Duragloss.com and then putting the front wheels up on ramps so that solution and rinse will drain easily. I happened to have a bottle of that since I use Duragloss products among others, and I sprayed liberally inside the pipes and outside where the black spots were. I let it sit for about 30 mins and then put my hose sprayer on "Jet" and fired away carefully, only because I wanted to get all the carbon I could see. you can certainly use a brush but I did not. The chemicals did the work! I am so so pleased with the results. Thanks to my buddy Mike and to my friend Jerry, owner and chemist of Duragloss. His products I swear by and I have expensive cars. If you do this, be sure to get the All Wheel Cleaner as the other options are for different wheel types and would not be good for this application. Good luck and PM me if you have any questions! Thanks!

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