About 4 years ago I bought this 6 hp leaf/yard vacuum. The bag deteriorated after a couple of years. We patched the bag and that worked for a while. A new bag cost $200, which was too much for me. Last fall I had the local sheet metal shop make a metal replacement. I works well, I needed some vent holes on the side for air to flow through. This cost $98 and will last as long as the engine.
My hubby is going to order a super duper leaf vacuum and mulcher.
The new metal leaf bag need lots of air flow. I have cut two 5" diameter holes with window screen over them. That is not enough. I need to double or triple that. The old bag was essentially completely porous.