3" Muffler Mod My Way
 

Thanks to Josh B. for the awesome write up on the DIY 3" muffler mod. I decided to tackle it myself, with a few minor changes I wanted to try, including installing a small bullet resonator and 4" tips. This was a ton of work, and I still have some slight adjusting to do to make everything line up perfectly, but overall I'm pretty happy.

Started with stock zr1 mufflers and my new HF welder. Feel free to talk shit about my welds if you can prove you can do better. I know they suck, but for a beginner they are good enough for work that can't be seen under the car.

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Cut off existing tips and valves. You can see how small the stock stuff is, less than 2.5"!

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3" Bypass pipe with bullet welded up.

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3" Bypass pipe installed back in muffler can. Had to clearance the other pipes a bit.

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One muffler had the baffles blown out, so had quite a bit of scabbing back together to do.

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Everything welded up.

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Painted with high temp bbq paint.

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Installed on the car.

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And here are a couple cell phone vids. Its probably 10% deeper than stock zr1 mufflers, and 30% louder. So on a H/C 750whp car it's racecar loud. Still has a bit of that tin can sound of the stock mufflers that I was hoping to get rid of. Still nice and quite when closed.

Definitely race car loud when open, but in a good way. Glad you took pics to document it all... otherwise, no one could appreciate the time and effort you put into it (engineering + labor/skill) to accomplish the goal. Just walking up or looking at it, it sounds/looks fantastic, but it's not fair to the work/time/process of putting it all together. Enjoyed meeting you this past Saturday.

I can vouch that it sounds fantastic and the video does not do it justice. A+ work!

well done - when I get home from work, I'll crank up the volume.

Excellent job and it sounds great! As I was reading your post and you mentioned you didn't think your welds were the greatest, I thought "he can just paint them flat black and hide some of the details." Then I got to the part where you painted them flat black...

Again, kudos to you!

Very nice David.
Yeah, the pics, vids do not do the car justice. You should post the ones where I am revving that B***!!! lol....

Not to be outdone, Wes, your ZR w the Akra's sounded sweet!! Marc and I were so unworthy.... pulling in and leaving the event...

The 2nd vid is you revving it. I think the camera mic just got blown out and it doesn't sound as loud as it really is.

David, awesome work! It looks great, I really appreciate you being able to retain the bi-mode setup and adding in larger tips.
Is it possible you could provide a parts list for the items you used: the valves, tips, pipes inside the muffler, etc?

Most ppl chop off the valves and just weld on larger tips and that sucks bc I like the ability to hit the foot switch i installed and pull into or out of my garage at 5am without pissing off the neighborhood.

Thanks!

You can just add the larger tips without removing the valves and doing the 3" bypass, several guys have done so. But here is all the stuff I ordered.

Bullets: Valves: https://www.ebay.com/itm/283340791427
Pipe 60* bends: http://www.acceltube.com/mm5/merchan...egory_Code=FAB
Tips: https://www.carid.com/jones-exhaust/...ification_mail
https://www.carid.com/jones-exhaust/...ification_mail

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:rofl: Just kidding...pretty decent work actually. Interesting idea on the resonators. :cheers:

lol yeah there was a lot of grinding done on the muffler case.

Those welds look like ass......

Great work, I like your twist on the mod. As you have seen, the ZR1 mufflers blow out the rear can inside the muffler. Now that you made room on the quiet pipes, Make sure those valves are open before you get on it and build boost. Or they will crack again.

I bet the video does no justice for how they actually are. Did you repack the fiberglass back in?

Bro, it sounds like a screaming Banshee...

Yeah basically always run with them open. Yes I put the fiberglass back in. Thought about adding more. Kinda wish I would have now. Thanks for all your photos and thoughts on the mod as well.