I owned a Honda S2000, and being a facelift model it had two large oval exhaust tips, located in the firing line behind the rear wheels, so the chromed tips became caked with tar particles, which melted on the hot exhausts, then solidified when the pipes cooled.
The way to get rid of the baked-on tar was as follows:
You need some paper kitchen towels, a can of WD40, one plastic bag per exhaust tailpipe, and some rubber bands.
Make sure that the exhausts are cold. Soak one or two kitchen towels with WD40, and wrap around the tailpipes
Cover each tailpipe with a plastic bag, and secure with the rubber bands.
Go and have a cup of tea, and wait for an hour or two. Then, remove the plastic bags, and wipe the tailpipes clean with some fresh kitchen towels, and use petrol or another solvent to make sure that all traces of WD40 are removed.
Finish the job with Solvol Autosol or similar metal polish.
Thank me later.