Right for the final time i am trying this chipping/weathering lark on the exhaust. I've cleaned up, re-painted with base colours of Vallejo black, flat brown and orange brown. Added the rust dust. Just need to seal it in with a varnish then i am going to give this AK Worn Effects stuff a go. All the reviews i've seen say it is good. I didn't go for the heavy chipping as i wanted something that would be a little more subtle.