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      04-14-2013, 09:18 PM   #21
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Drives: 2013 F30 335i MSport
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Originally Posted by RPM90 View Post
Just removing the damping material will change the sound, making it louder and perhaps even a bit deeper.

If you consider that low frequencies are also longer waves, then allowing that wave to travel through to the outlet without being broken up will result in a deeper sound. Long waves can also bend around corners like through the tubing. That's why in a house we can still hear the bass coming from the stereo even if we're in another room down the hall.
Your idea to close off those holes is a "sound" idea, as those holes are where the longer sound wave is being broken up.
That additional damping material further absorbs the broken wave energy to keep things quieter.

I think you're going to get a much louder and deeper tone, but will it sound pleasant? THAT is THE question.
If it does sound good I'll be surprised considering that manufacturers spend time tuning mufflers and exhausts systems not just for flow but sound quality. It'll be a very happy surprise if the louder sound is also a pleasant one. You may find that only closing half or one side of the holes will yield a better tone.
Maybe you should have done only one side at a time.
That way you would know if you're on the right track.
But, too late now. If the sound is ugly you could then try drilling some holes back in.

I had a Yamaha V-twin a few years back with a very anemic and very quiet exhaust due to the same type of design as our stock mufflers. People experimented and came up with some ideas. I used the recommendations and did the drilling. Yes, the sound was louder and deeper, but the quality of the sound sucked.
So, I opted for a set of low cost slip on mufflers made by Jardine. The result was louder, deeper, but a much better and mellower sound quality.
The best experimental experience I had was with my former Honda VFR750.
It's a V-4 engine. I had a nice though quiet Yoshimura slip on muffler.
One day I took off the slip on and fired up the V-4. WOW, man that engine had a cool sound and with just the headers the sound was glorious. But now way I could ride it around, it was just too freaking loud.
I've loved the sound of V4 engines ever since. Too bad they're not common. I'd love an auto maker to make a V4 for a car. That configuration yields great torque, and what a sound, think 2 V-Twins beating against each other.
I digress, sorry.

I want to hear your frankenmuff experiment. Let me know when it's done and I can come out and take a listen.
PM or email me.
Yeah it may indeed sound like crap. We shall find out soon. Im leaving the packing material in there, i think it will help with droning. Not sure if just want to do one side welding, and if there is little or no change because the sound is still escaping Ill be pissed lol. To reopen and reweld the muffler again will just be to costly to make the project worth wile and to proceed would just be throwing another $100-$200 to reweld the canister.

Im gonna pray that is sounds good, as I got my idea form an E92 M3 project I saw on youtube. The cut and replaced the perforated pipes instead of just welding the holes up, but those pipes were perfectly straight and easy to cut and weld. The F30 interor piping is curved and oval so to speak. Finding another pipe like that is a long shot and a waste of time and cash.

As soon as Im done Ill throw up a video. And youre more then welcome to check it out in person if it sounds good. Even if it sounds like crap Ill still post up the vids just to show you guys.
FBO-PS1 and stuff