Aight. Maybe some of you gents can help me out. I'm about to build/upgrade my exhaust. Right now I have a single 3" coming out the turbo and all the way out the back with a borla pro xs muffler and a vibrant resonator at the rear. What I'm doing now is putting a 1.25 exhaust housing on the turbo and its a 3.5" out. I want to take advantage of that because I'm pretty sure my backpressure is high as i'm running 20-22lbs of boost. I may go a little higher when i switch to flex fuel. So i'm going to run 3.5" all the way out the back. However, thats going to be loud, and I want it quiet, until i don't. So dualmode is what I plan. I already have a nice 3" electric cutout...but dumping under the car sounds like **** and rattles the whole car. SO I figured 3.5", then "Y" it into two 3" and one side go through either a round muffler on one side and bypass it on the other side with the cutout....merging back into the exhaust after the muffler. Problem is, I need a round, not oval muffler that is quiet...to accomplish this. OR I was going to build a square muffler with a dual 3" inlet/outlet and one side will be straight through.

Now my questions are, 1) any idea on a quiet muffler? 2) what about a straight through borla dual in/out 2.5" muffler? (2) 2.5" have roughly the same pipe area so it "may" flow about the same. OR 3) I could use a more common quiet 2.5" round muffler and bypass it with a 3" and that should equal the flow of a straight through 3.5"

The muffler is longways in the middle of the car. Thats the reason for doing it this way.

 

This is what I have now:

 

Magnaflow makes a single 3.5" dual 3" out mufller. You could probably reuse your existing tailpipe the for one side with a little massaging, then make a mirror image going out the other side.

 

Flowmaster makes a pair you might like. One is dual 3.00" in/dual 2.50" out (#530504), the other 2.75"in/dual 2.50" out (#527504). Both mild sound

 

That wont work.....how would I bypass the muffler? i dont want the cutout dumping under my car anymore. I want it merged back into the exhaust to come out the tailpipe......


I dont want dual tailpipes either, theres only one exit on my car.

 

ok, So looking at the cutaway of those mufflers, they have chambers in them. Impossible to slide a straight pipe through it.



So lets see if i can explain this well. If I were to do a dual in/out muffler, it would have to have a straight through perforated core, I could slide a piece of non perforated pipe through it, voiding the muffling properties of one side. Then I'd use my cutout to open the pipe right before the straight through pipe. and out of the muffler, they would join back together.

 

I don't think anyone makes a dual-in dual-out glasspack with parallel, non-intersecting cores. I think Magnaflow's dual-in/dual-out uses an X-pipe in the middle to even the pulses.
You're looking for a real oddball.

 

What if you rotated an oval muffler from horizontal by whatever degrees would allow clearance for the bypass pipe?

So for example, let's say there's enough vertical clearance to tilt it 45 degrees. Then re-bend that section to move the muffler over closer to the passenger side of the tunnel. A bypass tube would nearly be a straight shot from from the intermediate pipe to the tailpipe along the driver side of the tunnel.

 

unfortunately the driveshaft is right above the muffler

 

o yea, I’m aware. lol.

 

Flowmonsters by Holley are dual straight thru with no X Pipe

https://www.holley.com/products/exha...parts/12599-FM

 

thx. I did get excited for a second. Then I realized I bought that exact muffler and sent it back. That thing was so frigging huge! And omg it was heavy. It wouldn’t fit where it would need to go. Honestly it looks like I’ll be building a muffler.

 

Dynomax and flowtech both make a good turbo muffler that's quiet. The hooker Aerochamber is quiet. Since you're going to run a cutout you can afford to get restrictive muffler(s). Magnaflows are nice but are typically more expensive.

 

I used a Flowmaster 70 series on my Jeep, 2x2.5 piped in to a Y with a 3" output to the muffler about 10 inches of pipe from the Y to the Muffler I haven't finished the tail pipe yet just a elbow off the back of the muffler, its surprisingly mellow,, Have you considered something similar with a boom tube for the cut-out? The boom tube will still cut the edge off the noise but you'll still be pretty much wide open. There are a couple mufflers out there with the bypass built in to the muffler, including the valve.

Flowtech sells one as well.. I searched for "Muffler with Bypass" several amazon hits..

 

FWIW, a bit of a different setup, but I have been trying to quiet down my LSX/LSA 660rwhp Impala with dual 3" exhaust and I've been through a few different combinations so I can weigh in on what worked and what didn't. I should say first I couldn't run an oval/rectangle muffler because of my chassis mounted sway bar clearance, but before I installed the sway bar I ran two Spintech XL sportsmans (supposed to be the quietest spintech muffs) and they were way too loud.

I then tried out the following combos, i'll rate them in terms of volume

Sportsman XL's plus ETC brand stainless resonators (good luck finding them, got them from our local speed shop) - still too loud inside and out
Borla 5" bullet mufflers - not much different than the 4" magna flow
Magnaflow 4" bullet mufflers- much quieter than the Spintech's chambered both inside and out, the magna flows without the resonators was still quieter than the spintechs with resonators.

So I installed the two 4" magna flow bullets going back to my two ETC resonators but it was still too loud for me.

I then welded in two Vibrant mini bullet race mufflers up front after the collectors and it definitely took a little bit of the edge off part throttle. WOT still too loud.

My latest combo is Vibrant mini race bullets into magnaflow 5" bullet mufflers (swapped the 4" ones off for the larger diameter 5") and then into the ETC resonators. I really like this combo. It's still got some volume to it, still screams WOT but part throttle it sounds more like that a typical bolt ons car would sound like. Pretty quiet for a 660rwhp car considering the whole system is really just straight through piping.

A few things I have learned is that there really is no difference between most "resonators" and "bullet mufflers". Typically, on factory cars, resonators are hollowed out sections designed to alter sound but not necessarily muffle all frequencies but when you get into aftermarket, I have found very few "resonators" are anything but glass packed bullet mufflers (i.e; perforated tube that leads into a chamber with steel wool packing). The aftermarket seems to use the two terms interchangeably

Volume (i mean that as in size) and packing material are your friends. Chambered mufflers won't quiet things down as much as steel wool packed mufflers willl and the larger the muffler you can fit, the better.

If you want a very quiet, but very free flowing straight through exhaust system, I would recommend first fitting the largest bullet or oval straight through style muffler you can fit and then adding another smaller "resonator" (and by that I mean bullet muffler) before somewhere as far up the pipe as possible giving the exhaust less time to resonate in the pipe before hitting it and then adding another after the muffler to do the same on the way out.

The vibrant mini bullets are a great choice for their size and ability to fit them in tight spaces but it also obviously will do the least of any bullet muffler to quiet things down because it's so small. If you can fit another larger bullet muffler, maybe even a 4" OD body magnaflow somewhere in the pre muffler piping I think you will get this thing down to a pretty reasonable volume.

 

Moving the muffler further back in the car will help. Get it out from under the passenger compartment.

 

i think that’s my plan now

 

Flowmaster Part # 717900 ..... I think you could build something like this.. for less money..

 

Has anyone tried Thrush's 3"x25" glasspacks? Seems like they would have negligible restriction, but that just makes me wonder whether they are actually any quieter than a straight pipe.
Example: https://www.summitracing.com/parts/wlk-24242

 

If you still have the red door panels please contact me , thank you