They had some spots near the collector that were pitted and surface rust between pipes was the worst of it. The rest was scuffing the original coating really. I spent a week sanding, grinding, and wire brushing. Then went back the day of the first coat to sand any new rust that was trying to start back again and really clean any residue. 2 light coats in as many days and then a final coat after the 7 day cure. The paint recommends a 0.8mm nozzle that requires some babying. Clean up prolly took a 15 minutes per coat and maybe 3 hours at the end. Its therapeutic right? .....