Hi, I have an old exhaust exit hole on the drivers side from an old engine. It is currently covered with a vent, but looks a bit rubbish in my opinion.
How easy/what's involved in re-skinning the side panel?
Thanks
Liam

Depends how it was fitted!
If you're lucky, it will be held on with pop rivets only - these can just be drilled out with the correct sized bit (squirt some waxoyl in one of the holes to stop the ends rattling - not that you'll hear them anyway) and the panel will just come off.
If you're unlucky, the builder will have used polyurethane sealant between the panel and the frame - that's a nightmare to deal with (been there, done that...)

If it's fibreglass and you can get the correct colour gelcoat, I'd fill the existing panel in place.

Use a sheet of polypropylene (check its that which won't bond to gelcoat) and temporarily attach it to the outside of the panel. Use a thick layer of gelcoat from the inside then build up with fibreglass. Remove the polypropylene sheet and sand/polish. It'd be worth angling the existing edges of the whole to ensure a good bond.

If you need to do any touch ups where old gelcoat meets new, you can then do that from the outside.

I had to remove a bonded on panel and despite my best efforts pretty much destroyed it in the process.

I got a marker pen and wrote 'No longer in use' above an exhaust hole from an old engine