Quickboost is well known for creating nicely detailed drop-in replacement parts to enhance the detail of plastic models. They have released a set of gun barrels for the Mirage III, for either the Eduard or the Hobby Boss kit. It might be possible to use this set with the Italeri Mirage IIIE, but I am not sure.
The cannon barrels are perfectly cast in grey resin, with a smooth, bubble-free finish. The molding includes two side walls to prevent accidental damage of the parts while in transit or storage. Removal of the parts should be easy, with either a hobby saw, or even by scoring with a #11 blade, if you take your time.
You can compare the resin parts with the plastic ones provided in the Hobby Boss kit. The main difference you’ll see is the muzzle brake detail and a much finer cannon barrel.