I have previously, ground out all the rust on the old Thunder and it hadn't come back after 9 months including driving it every day during the winter, but my Red Puma is in overall far better condition. I heard someone say that the earlier Puma used German steel and didn't rust as much and compared to my 2001 MSB Puma (arches are rust free !), the Red (1999 built) certainly has less ferocious rust. It may be that the previous owner sprayed old engine oil underneath every year, but in areas that he hadn't done, like above the exhaust heat shield there was minimal surface rust in comparison to the MSB one.