In order to install the BW Racing X-pipe, start by removing this underpanel.
I was pleasantly surprised with how nice this panel was, being a factory piece. I was especially impressed with the velvety material on the outer side and the provisions for airflow from the front. It really cleaned up the underside for the E90 M3—just one of those details I like to notice.
With the panel out of the way, you’ll have access to the 02 sensors.
Sometimes people get a little weird about aftermarket sensors, but in this case you can see the ones we got from Sparkplugs.com are identical to the factory ones. They even have the same part number, just not the same price.
And, they’re even made in Germany, in case you’re still [that] skeptical.