When Dyson says their vacuums don't lose suction that isn't exactly true. Over time the suction will decrease and replacing these two filters will restore it. They are a breeze to replace, about a 10 second job. The top filter simply pulls straight out and the larger rear filter twists about 45 degrees and pulls off.
If your Dyson doesn't seem to be working as well as it once did try this filter set.
My Dyson V8 was starting to cough and wheeze on a regular basis. Usually just putting in a clean pre-filter remedied the situation but after a year of regular usage I realized it was time to get a new HEPA post filter. I purchased this particular brand based on the mostly positive reviews. It was half the price of the original OEM version and hopefully it will last just as long. The first time I vacuumed with the new filter I noticed a dramatic improvement in suction and overall performance of my Dyson. Since the pre-filters are washable I always start with a fresh one so this leads me to believe I need to change the post filter even more often. Dyson recommends changing the post filter once a year but I may do it once every 6 months after experiencing how much better it cleaned with a new one. I would highly recommend this particular brand of Dyson post and pre-filters. The quality and performance seems every bit as good as the Dyson original filters.
My Dyson V7 started pulsing when the exhaust filer, which is not cleanable, got full of micro particles. Didn't really need to replace the intake filter, because it's easy to wash, but this was such a good deal I bought the pair. Very happy with the purchase.