[Triniti X4 M40i]

Originally Posted by Lotus99

Easy peasy... Just did mine a few days ago. There's a little more sound, which is nice.

First of all, if you are curious what the before/after sound will be like, turn on your car, then go to the back, and look at the exhaust pipes. You'll see the metal valve attached to the outer pipe, with a little metal arm / actuator outside of it, and a black rubber line attached to it. You'll see the metal valve attached to one of the pipes, with a little metal arm / actuator outside of it. By default, that arm is extended which keeps the flap closed. If you push it in with your thumb, it will open the flap and you will hear what it would sound like. Note that if you do this test when the engine is cold, it will sound louder than under normal operating temperatures.

Unlike in the E9x series, where vacuum is used to keep the flap closed, and by Disconnecting the vacuum line, the flap will remain open, is the opposite in our cars and the E6x ones (what I used to have). There is a vacuum line coming from the engine, going to a little electrical valve controller behind the trim panel on the left side in the trunk, and there is another line going down to this exhaust flap valve.

All you do is disconnect both lines going to this valve controller in the trunk, and connect them to each other using a 1/4" coupler, and that puts constant vacuum on the exhaust flap, therefore keeping it open all the time.

You can reach the electrical controller by just opening the trim panel, however there was in a lot of room to work and the lines are on pretty tight, so I took out the plastic bucket that was there, which is held in by a few plastic rivet type fasteners, and a torx screw.
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Originally Posted by Lotus99

Easy peasy... Just did mine a few days ago. There's a little more sound, which is nice.

First of all, if you are curious what the before/after sound will be like, turn on your car, then go to the back, and look at the exhaust pipes. You'll see the metal valve attached to the outer pipe, with a little metal arm / actuator outside of it, and a black rubber line attached to it. You'll see the metal valve attached to one of the pipes, with a little metal arm / actuator outside of it. By default, that arm is extended which keeps the flap closed. If you push it in with your thumb, it will open the flap and you will hear what it would sound like. Note that if you do this test when the engine is cold, it will sound louder than under normal operating temperatures.

Unlike in the E9x series, where vacuum is used to keep the flap closed, and by Disconnecting the vacuum line, the flap will remain open, is the opposite in our cars and the E6x ones (what I used to have). There is a vacuum line coming from the engine, going to a little electrical valve controller behind the trim panel on the left side in the trunk, and there is another line going down to this exhaust flap valve.

All you do is disconnect both lines going to this valve controller in the trunk, and connect them to each other using a 1/4" coupler, and that puts constant vacuum on the exhaust flap, therefore keeping it open all the time.

You can reach the electrical controller by just opening the trim panel, however there was in a lot of room to work and the lines are on pretty tight, so I took out the plastic bucket that was there, which is held in by a few plastic rivet type fasteners, and a torx screw.
.

Great tip. Will have to try on my '16 F26 M40i. Did you get any faults or dashboard errors after doing this mod?