All I can say is that I have noticed that the old vacs to which I have adapted HEPA filter bags to stay clean inside where just one bag full using a paper bag leaves the vac bag chamber and motor compartment with a fine layer of dust that requires a field strip and cleaning. Therefore all vacs get HEPA bags one way or the other.
And, yes, Sebo_Fan I am always thinking about ways to improve the performance of my motorcycles, cars and vacuums. It's how I get my kicks. I'm a hot rodder at heart. I have some interesting frankenbikes that incorporate parts from many years and many models of different motorcycle to create a very nice custom, and by this I mean a functional day to day commuter, sport tourer and weekend canyon scratcher. I don't hang parts on a bike for the sake of looks or that detract from function. I do make bikes that function better than the original did with all my mods aimed at street riding, not the race track. One of my favorite Beemers has parts from a ten year spread of different BMW models along with a custom length shock made for me to my spec by Works Performance in Los Angeles. I have a most unusual V-Rod sport tourer that I can swap between lockable hard luggage, soft luggage or no luggage in maybe five minutes, along with two different windscreens that interchange in minutes, a repadded seat, custom air box bra to allow a tank bag to strap on (you seldom see a Harley with a tank bag), different sized wheels, more custom length shocks from Works, fork work from another suspension company, etc. Fitting the wheels required innovating custom axle spacers, calculating overall gearing for those wheels with different combinations of pulleys, eventually fitting a rear pulley from a Japan market Sportster (but since Sportys and V-Rods have their rear pulleys on opposite sides I had to flip all the rubber isolator blocks around inside the housing) and I had to have a belt for a Victory motorcycle narrowed down from 28 mm to 1 inch to fit the Sportster pulley. There as no Harley belt the length I needed so I had to find one with the same tooth pitch Harley uses with the right number of teeth. Only Victory made such a belt. All of this worked out wonderfully and the bike will run with any sport tourer in the twisties. I can ride it from California to Utah on back roads in one day comfortably. When I first bought the V-Rod I was a little dismayed that it didn't even have storage for the registration and insurance paperwork. It didn't take long to figure out that Harley expects you to modify their bikes twelve ways from Sunday. Once that bulb clicked on the real fun began.
I take the same approach to vacuums, studying different parts from different vacs to see what works best. I don't think backing a cheesy open cell foam pre motor filter with a modern blown glue filter and replacing the crappy degradamatic exhaust filter with something more durable and sometimes even washable is going to harm the vacuum. I have noticed no difference in the performance of my Epic 8000 by adding a Kenmore CF-1 filter to the back of the bag chamber to protect the motor. As it turns out what I did is not much different than the accessory charcoal filter Aerus Lux sells for the same purpose, though I didn't know that when I came up with my solution.
Like I said there Sepo_Fan, untighten the ol' sphincy and have some fun. You can modify your stuff and bad things don't necessarily happen. Engineering is all about compromises. You can change things and alter those compromises to your benefit. And have some fun in the process.
