Although this rubber boot did its intended job, and was still an improvement over the cracked rubber boot it was replacing, I found that the fitment was not perfect on my BMW E46 and the boot had to be physically stretched in order to fit snugly over the MAF so you can tighten down the hose clamp which keeps it in place.
Because this boot uses thinner, softer, more pliable rubber than the OEM boots when everything was reassembled, the hose no longer held its cylindrical shape, and was squashed vertically on the end closest to the MAF housing, reducing the diameter of the boot and thus restricting airflow.
I took my time installing and reinstalling the boot several times at slightly different angles in an attempt to get it to fit right before I frustratingly came to the conclusion that this was an inherent problem due to the rubber being too thin and pliable. This boot would be perfect if it was a little thicker/more rigid. But for the price it is an acceptable remedy. I have now ordered a genuine boot from BMW at a cost of £25 and will update this review with the results from OEM vs this aftermarket part.
This was bought as a replacement for the originals that had perished are were causing brake problems due to lack of vacuum in the brake booster.. Fitted well and quickly and immediately solved the problem.