[6629matt]

Hi everyone. I have never posted before but wanted to share a few things I discovered this weekend while putting an axle back 2015 335 exhaust on my 2015 328i. I read everything I could find on this forum before I did the modification and it was extremely helpful. there were a couple of surprises however and I wanted to share them with anyone considering doing the same thing. I love the way it turned out and am very happy I decided to do it. I bought a used 2015 335 axle back on Ebay for $195.00 including shipping. A diffuser on Ebay for $117.00 including shipping and a stainless clamp on Ebay for $7.99. I rented an exhaust kit which contained a cutter and some expansion tools from Autozone for free. I had the old exhaust and diffuser off in about a half hour and that part was very easy. I decided to unbolt the hangers and transfer them to the 335 exhaust. the 335 exhaust was not as long as the old 328 exhaust so the studs went into the rubber mounts about 3/4 of the way, which seems plenty good. I will try to attach pictures. the problem was that the pipe coming out of the muffler and the exhaust pipe (midpipe?) were at totally different angles so there was no way I would get the clamp to work. I am lucky to have a small shop near me that does custom exhausts and could weld stainless. I drove the car to them with the exhaust installed but the pipes not connected. The guy[IMG]undefined[/IMG] quoted me $60.00 to make the connecting pipe and weld it. I was so happy he did it for me on a Saturday with no notice that I slipped him a hundred cash. I did have to buy a 3" dia 18"l. piece of stainless exhaust pipe from Autozone for him to use though. that cost $27.99. The exhaust tips were another small issue. it seemed that I could either have them centered in the cutouts or the same poke, but not both. I chose centered since I am going to put some aftermarket carbon fiber tips on anyway and will adjust it then. in the meantime I just popped the OEM chrome tip on the left out a little bit and it looks fine. I hope this helps someone.

[kobluna]

I'm going to do the same but I have sport line 320i. That means that I have only one exhaust tip on the left and I don't have removable diffuser. Could you measure the distance between left parking sensor and left exhaust tip? See the picture. Please do at least x measurement and maybe z as well, just to make sure. Or if you come up with another easily measureable distance it's fine as well.

If that distance is close enough to my current left tip then I only need to make one more cut to right hand side of the bumper. Otherwise I need to buy a whole new bumper which means that it's not worth it.

[6629matt]

Sure. I'm at the gym this morning, but when I get home I'll take some measurements for you.

[rjd_F30]

I have no interest in doing this conversion, but this would be a helpful thread if I was. Good write up

[6629matt]

I measured the z dimension from center of the sensor to center of the tip is 11". I also measured center of left tip to center of right tip, which is about 32-1/2". the tips are equidistant from the center of the car. I hope that helps.

[CandyRedRC46]

Looks great from the back, but I would be concerned about the exhaust hanger not being fully inserted.

[6629matt]

Originally Posted by CandyRedRC46

Looks great from the back, but I would be concerned about the exhaust hanger not being fully inserted.

I agree, that was also a concern of mine. the exhaust specialist who welded my pipes said it was fine though. It is about 3/4 of the way in both rubber grommets, so even if it shifted all of the way to one side it would still be firmly in the other. I do plan on inspecting it regularly though.

[6629matt]

Originally Posted by rjdnyy224

I have no interest in doing this conversion, but this would be a helpful thread if I was. Good write up

Thanks. Several other posters of the same mod did a much better job describing all the steps, tools, etc so I just wanted to add some of my observations and discoveries along the way that I didnt think were discussed much in their posts. Overall I am very happy with the way it looks and sounds.

[kobluna]

Originally Posted by 6629matt

I measured the z dimension from center of the sensor to center of the tip is 11". I also measured center of left tip to center of right tip, which is about 32-1/2". the tips are equidistant from the center of the car. I hope that helps.

Thanks Unfortunately the z dimension for me is 13" so I need to figure out something else than stock 335i muffler.

[6629matt]

Originally Posted by kobluna

Thanks Unfortunately the z dimension for me is 13" so I need to figure out something else than stock 335i muffler.

I was wondering if your sensors might be located differently since it is a different bumper type. That's why I gave you the equidustant center to center dimension. so if your cutout was centered at 16-1/4" from the center of the bumper...

[kobluna]

Originally Posted by 6629matt

I was wondering if your sensors might be located differently since it is a different bumper type. That's why I gave you the equidustant center to center dimension. so if your cutout was centered at 16-1/4" from the center of the bumper...

Yep, thanks again. If I measured it correctly my center to center dimension would be 37½" so few inches more. And indeed, if I look the pictures of 335i the tips seems to be more centered than my single tip.

Maybe I can get muffler shop to cut other outlet pipe from muffler and get an extension piece. Muffler shop needs to modify the mounting points as well so then the whole muffler would be slightly off centered but that is not visible outside of the car. Or just cut both outlets and not modify mounting points, which ever is easier. Might still be cheaper than getting a new bumper.

[N26Ghost]

Great write up! I did the same and never looked back. Currently have the 335i muffler and M Sport diffuser, but I still have an itch to go MPE...we shall see how long it lasts, lol.

[Fronttwelv]

Originally Posted by N26Ghost

Great write up! I did the same and never looked back. Currently have the 335i muffler and M Sport diffuser, but I still have an itch to go MPE...we shall see how long it lasts, lol.

Just gut the 335 muffler.

[Littlebear]

Originally Posted by CandyRedRC46

Looks great from the back, but I would be concerned about the exhaust hanger not being fully inserted.

For the 'left' or US driver's side muffler mount, there are two mount plates available. I think if you use the alternate plate & rod (left one in pic), the rubber hanger might go on all the way. It might also affect the side to side tip position, though....

Murf

[lfepro.g]

If anyone is interested in doing this, I'm putting up my 435 muffler with diffuser for sale ! Just bought a Borla Catback so I have no use for it!

[757seaman]

Interested in doing this to my 428i. Haven't done any extensive research but a couple questions are will it possibly throw any CEL's? Does it sound any different

[6629matt]

Originally Posted by 757seaman

Interested in doing this to my 428i. Haven't done any extensive research but a couple questions are will it possibly throw any CEL's? Does it sound any different

No CEL and it sounds slightly deeper and louder, but hardly noticable. I couldn't be more happier. I would line up a local stainless welder though. You can hook it all up and drive it there loose if it's not far or just have them do it.

[N26Ghost]

Originally Posted by Fronttwelv

Just gut the 335 muffler.

Seriously considering this...

Though the sound is better than my stock 328i muffler...it still isn't what I wanted it to be. I'd like the true dual personality difference. Comfort/Eco Pro to be hushed and Sport to be angry and burbly.

I've watched a few vids of people doing this mod and will be reaching out to my local shop to get a quote on what they'd charge to do the work.