[DASN54]

Anyone know what the internal piping size inside the muffler is? Im doing a PE mod this weekend and need to know what size of pipe to pick up, couldnt find anything regarding this. Thanks!

[stewbets]

2-1/2" ID pipe worked for me. I bought an 18" 2-1/2" ID pipe and a 2-1/2" ID x 2-1/4" ID adapter and that did the trick. It's not a tight fit, but it was certainly close enough for me.

[DASN54]

Cool, thank you sir!

[stewbets]

No problem! Are you planning on hardwiring a switch for the flap valve, or using a remote?

Or are you just gutting both sides? I just gutted the driver's side and really like the flexibility of having it loud or quiet.

[DASN54]

Originally Posted by stewbets

No problem! Are you planning on hardwiring a switch for the flap valve, or using a remote?

Or are you just gutting both sides? I just gutted the driver's side and really like the flexibility of having it loud or quiet.

I was planning on just doing what this guy did and replacing perforated piping on both sides and keeping all packing. Also, since Im e90 replacing the stock resonator with an x-pipe.

https://www.e90post.com/forums/showt...ght=bmw+pe+mod

But you got me thinking about retaining the flapper. hmmm......

[stewbets]

I don't really know how much of a difference in volume it is between doing one side or both, but I'm satisfied with just the one side. You could always try one side at a time if you're on the fence at all. I just really like the option of a much quieter cold start if the situation calls for it, but maybe you don't need that.

[type-dRew]

Originally Posted by stewbets

I don't really know how much of a difference in volume it is between doing one side or both, but I'm satisfied with just the one side. You could always try one side at a time if you're on the fence at all. I just really like the option of a much quieter cold start if the situation calls for it, but maybe you don't need that.

Its a large difference with both. The right side has more muffling capability. The side with the flap is just a small resonator that gets cut out of the larger exhaust box.

Its made that way for the same reason youre doing it, but just oem. With it closed, its quieter.