Z4 35is muffler delete mod

[airwalk776]

With the lack of affordable good sounding exhausts out there for these cars been tempted to try the muffler delete mod where you cut out a section of pipe inside the muffler and replace it with a solid pipe. Anyone have experience with this or know a shop that can do it near NJ.

other suggestions welcome

[taranfx]

rather go catless downpipe. sounds awesome with 35is

[airwalk776]

Originally Posted by taranfx

rather go catless downpipe. sounds awesome with 35is

Originally Posted by taranfx

rather go catless downpipe. sounds awesome with 35is

Should have mentioned in my OP. I have vrsf careless downpipes. ER FMIC. ER charge pipe. COBB STAGE 2. KN air filter. Golf tee mod done.
Rest of the exhaust is stock 35is exhaust.

Just attempting to get it's little more sound out of the exhaust.

[glutton4punishment]

I just did the muffler modification to my 2011 Z4 35i. I first tried the secondary cat delete by replacing the center section with the Supersprint straight pipes.

http://www.turnermotorsport.com/p-39...ry-cat-delete/

The secondary cat delete helped but I still wanted a more aggressive sound. I saw a couple of You Tube videos on how to do the muffler mod and decided to give it a try. I was unable to find a video specifically for the Z4 so I was kind of going at it with half a clue of what I was doing. After cutting the muffler open what I found was that my mufflers were much tighter in regards to room on the inside for being able to weld a replacement pipe in place of the perforated section. I had a piece of pipe that was the right size that I was going to use but saw no way to be able to weld it 100% all the way around without cutting open both sides of the muffler which was something I didn’t want to do. I felt that not being able to weld in the new section 100% around could compromise the strength of the muffler or lead to rattles. So instead of replacing the perforated section I decided to cover it up. I took the pipe I had and cut it to the correct length to be able to cover the perforated section. Then I used a thin cutoff wheel on my die grinder and split the pipe into two half pieces. Because the pipe was very close to the same size as the perforated section in the muffler, I needed to spread the two halves just enough that I could place them over the top of the perforated section. I clamped them down tight with one seam of the two half sections very tight together facing up where I could weld them together. On the other seam there was about a ¼ or bigger inch gap. I first welded the tight seam together being careful to not weld through. My goal was to weld the tight seam together so I could later spin the pipe cover around so the wider gap would be up where I could weld it next. After I welded the tight seam, I unclamped the cover and using some channel locks I spun the half-welded pipe so the wide gap was up. Next, I welded the side with the wider gap by once again clamping it tight to the perforated section. I tried to keep it as tight as I could to eliminate rattles. This time I welded the edges of the cover pipe to the perforated section. This not only attached the cover to the perforated section it also welded the perforations shut at the same time. I also welded the ends as far as I could reach around. I was able to get almost ¾ of the way around the ends. After the covers were welded into place, I welded the muffler skin back into place. Here’s a tip. When cutting the skin of the muffler use as thin a cutoff wheel as you can. These muffler skins are not very thick and are pretty hard to weld back together. The tighter the seam the better.
Do I like the outcome? Yes. The sound is much more pronounced and aggressive when you get on it. But it’s still not obnoxious when taking it easy with no drone. Plus it has a subtle crackle on deceleration and I really like that. Is it perfect? No, it is not. When you really get on it, it will pop when shifting. Almost a backfire. Let’s face it a nice engineered system would no doubt sound better. But it would also cost a couple thousand. This was a cheap alternative to a performance exhaust system. I call it a cheap thrill.

[airwalk776]

Originally Posted by glutton4punishment

I just did the muffler modification to my 2011 Z4 35i. I first tried the secondary cat delete by replacing the center section with the Supersprint straight pipes.

http://www.turnermotorsport.com/p-395168-e89-z4-35i35is-supersprint-section-1-straight-pipes-secondary-cat-delete/

The secondary cat delete helped but I still wanted a more aggressive sound. I saw a couple of You Tube videos on how to do the muffler mod and decided to give it a try. I was unable to find a video specifically for the Z4 so I was kind of going at it with half a clue of what I was doing. After cutting the muffler open what I found was that my mufflers were much tighter in regards to room on the inside for being able to weld a replacement pipe in place of the perforated section. I had a piece of pipe that was the right size that I was going to use but saw no way to be able to weld it 100% all the way around without cutting open both sides of the muffler which was something I didn’t want to do. I felt that not being able to weld in the new section 100% around could compromise the strength of the muffler or lead to rattles. So instead of replacing the perforated section I decided to cover it up. I took the pipe I had and cut it to the correct length to be able to cover the perforated section. Then I used a thin cutoff wheel on my die grinder and split the pipe into two half pieces. Because the pipe was very close to the same size as the perforated section in the muffler, I needed to spread the two halves just enough that I could place them over the top of the perforated section. I clamped them down tight with one seam of the two half sections very tight together facing up where I could weld them together. On the other seam there was about a ¼ or bigger inch gap. I first welded the tight seam together being careful to not weld through. My goal was to weld the tight seam together so I could later spin the pipe cover around so the wider gap would be up where I could weld it next. After I welded the tight seam, I unclamped the cover and using some channel locks I spun the half-welded pipe so the wide gap was up. Next, I welded the side with the wider gap by once again clamping it tight to the perforated section. I tried to keep it as tight as I could to eliminate rattles. This time I welded the edges of the cover pipe to the perforated section. This not only attached the cover to the perforated section it also welded the perforations shut at the same time. I also welded the ends as far as I could reach around. I was able to get almost ¾ of the way around the ends. After the covers were welded into place, I welded the muffler skin back into place. Here’s a tip. When cutting the skin of the muffler use as thin a cutoff wheel as you can. These muffler skins are not very thick and are pretty hard to weld back together. The tighter the seam the better.
Do I like the outcome? Yes. The sound is much more pronounced and aggressive when you get on it. But it’s still not obnoxious when taking it easy with no drone. Plus it has a subtle crackle on deceleration and I really like that. Is it perfect? No, it is not. When you really get on it, it will pop when shifting. Almost a backfire. Let’s face it a nice engineered system would no doubt sound better. But it would also cost a couple thousand. This was a cheap alternative to a performance exhaust system. I call it a cheap thrill.

Thank you for the review. I've been wanting to do this for a while now but can find any shops in nj to do it.

[ray7792]

I got my secondary cat delete by Need Powder Coating in Newark if you're in central/north Jersey. They have a good reputation, personal experience and of those I know has always been good.

But man you'll basically be straight piped then, save for the secondary cats...Have you ever owned a straight piped car or been inside a straight piped 335i? It is not great man. These cars have pretty decent sound deadening so drone isn't absolutely terrible but it just doesn't sound clean man. To each their own though.

[airwalk776]

Originally Posted by ray7792

I got my secondary cat delete by Need Powder Coating in Newark if you're in central/north Jersey. They have a good reputation, personal experience and of those I know has always been good.

But man you'll basically be straight piped then, save for the secondary cats...Have you ever owned a straight piped car or been inside a straight piped 335i? It is not great man. These cars have pretty decent sound deadening so drone isn't absolutely terrible but it just doesn't sound clean man. To each their own though.

I drove my z4 3 days in a row and I think you might be right. Now thinking about it having straight pipes prob not a good idea

[ray7792]

Originally Posted by airwalk776

I drove my z4 3 days in a row and I think you might be right. Now thinking about it having straight pipes prob not a good idea

hahaha make the final decision in the spring when you can put the top down again