Aim for a quiet exhaust...

[TurboTrader]

I'm designing a full 3" exhaust from the ground up for #145, Turbo-back. I am also aiming to keep it as quiet as possible while increasing the size/flow substantially. Currently I have a 2.5" DP back, stock DP with a 12" resonator and Magnaflow dual outlet muffler. It sounds great, and cruising speed on the highway, I am still able to maintain a conversation with my passenger, it's actually somewhat mild, but can still be heard a couple blocks away indoors.

I may be a bit different, but I love fast, and although I do love fast and loud, at least for my weekend car, I'm getting a little older to where I don't wish to turn my stereo loud enough to drown out the exhaust drone, and the local Hondas with coffee can exhausts, loud and slow, I am choosing a different route.

So, anyway, I've been piecing together my custom exhaust for the past month and hope to finish it off in the next couple weeks. It started off with a 3" DP, 14" Magnaflow Resonator, and my latest purchase, to finish it out, I think I grossly underestimated it's size, but am hoping I can still fit it in. Both resonators being a perforated core, from what I have read, should restrict the exhaust flow little if any, and should get me where I need to be sound wise.

Well, this is where I underestimated exactly how massive a 30" resonator actually is. It seems pretty huge to me. The original plan was to put it around the stock Cat location, but with the Carrier bearings on the front part of the driveshaft, I'm unsure if it will not be too long.

My first thought was to cut the DP down and fit it just after the flex section and in the cat area, which would place it just before the first carrier bearing, and hopefully high enough i don't scrape it on speed bumps and such. I measured and could just about pull it off. The other option, is to mount it to the rear of the first carrier bearing and it would just clear the second, but I'm unsure of clearance. Both resonators are 6" in diameter, and I have the 3" V-band flange to mate the DP to the first resonator. I'm still undecided whether I will also run a muffler in the rear, or not, so I plan to have the exhaust done just to the rear axles and will decide if I like the sound or not, and may leave the muffler out entirely.

Opinions?

 

So your upgrading to 3in. and hoping it's quieter? /ubbthreads/images/graemlins/dunno.gif /ubbthreads/images/graemlins/idea.gif

 

[2of9]

if it's quiet enough without the the muffler, I'd say go for it but I think it'll be slightly louder. I currently have 3" straight all the way with the apexi n1 muffler tip. That's too loud for me. When I had the magnaflow high flow cat + magnaflow muffler, it was nice and "quiet" on the highway. Get a video up if you can /ubbthreads/images/graemlins/smile.gif

 

Quieter than a typical 3" exhaust I think he means. If that F*ing huge resonator doesn't do it, what can?

 

[TurboTrader]

Exactly. A full 3" will obviously flow better than a full 2.5", so I'm aiming to have the benefit of going bigger without the unbearable noise of doing so.

 

[thedsmguy]

I'm diggin the bathroom floor picture with the socks and such.

How about doing two smaller resonators and a muffler? I've seen some pretty quiet 3" systems built it can be done.

 

Here's what I don't understand abou the people that want max performance and demand stock noise: Why dont you get a 3in downpipe with an electric cutout and then have a stock exhaust for the rest of it? Best of both worlds. /ubbthreads/images/graemlins/dunno.gif

 

[TurboTrader]

Quoting thedsmguy:
I'm diggin the bathroom floor picture with the socks and such.

How about doing two smaller resonators and a muffler? I've seen some pretty quiet 3" systems built it can be done.



Actually, that's our bedroom floor, we have tile throughout the house, and until the wifey picked up the laundry, our bedroom floor was quite messy. LOL.

I still have the 12" Magnaflow resonator as well, also 6" in diameter with 3" inlet/outlet, and I plan to fit both in. The reason being is that I have heard different sized resonators muffle different frequencies, and if with the two resonators, I'm still not happy, I will have a muffler put in as well, if I like it as is, I will put a Y-pipe at the end to maintain the stock look.

Quoting crankwalk:
Here's what I don't understand abou the people that want max performance and demand stock noise: Why dont you get a 3in downpipe with an electric cutout and then have a stock exhaust for the rest of it? Best of both worlds.



I can't speak for everyone, but I didn't much like the stock sound, even stock, it was much too tinny for my liking, even with the stock Cat and factory resonator and muffler. I was pretty pleased with the sound when I went full 2.5" DP back with the 12" resonator and Magnaflow dual outlet muffler. It was nice, deep and throaty, but with the crush bends and that it is only 2.5" I would like to do much better this time around. I'm looking for similar, or more, if I can have more quietness while having much more flow.

As far as a cutout, I thought about doing so, even looked into an electronic one, but decided that I want the flow and top end at all times, and not just when I have the flapper opened, or at the track, since as little as I can make it to the track, I enjoy the Galant on the road more of time than I ever will at the track.

That's not to say I won't do a cutout in the future, but for now, I think it will be a killer setup and quieter than any full 3" around.

 

[thedsmguy]

I'd like to see how this turns out for you. Is there any way you could measure the noise output?

 

[TurboTrader]

I will certainly be sure to do so, and also get some nice sound clips inside and outside.

I'm still trying to source a shop that can do true 3" mandrel bends local, shouldn't be hard, but I only called a couple today. Most around only do crush bends from what I can tell so far. If that fails, I figured 3 45-degree stainless bends should do the trick, and I have found plenty of 45 degree mandrel bent stainless pipes in various lengths I could purchase and have welded together, but I would much rather 1 solid piece from the 2nd cat to muffler.

I put the car on stands and got some good measurements. If I use the 30" resonator, it will need to be just to the rear of the second carrier bearing to be able to tuck away for sufficient ground clearance, and the smaller resonator will be going just to the rear of the DP. I've also decided I will be needing another V-band. I'll be putting one from the DP to first res. and a second just before the muffler, and that should allow for easily dropping the exhaust down should I need to, and I will, especially when I swap the 4-bolt in.

 

Run the flapper based on throttle position, not commanded position. Any time you hit above a certain throttle it opens.

 

[ozyvr4]

I run a full 3" exhaust ( 3" dump, 3" hi flow cat , 3" resonator & 3" Lukey muffler) not one those stupid cannon things. When I drive with the windows up I can hardly hear it. the loudest part of the car is the intake.

 

[TurboTrader]

That's what I'm aiming for, minus the cat, we don't really need one in Florida. Of course a quiet 3" can be done, and that's what I plan on.

 

I'm after the same thing - hate the highway drone! The muffler that I was thinking about is the Cherry Bomb vortex. I have it on my v6 Toy truck (3" cat back) and it has a good deep sound. It is basically a turbo muffler with glass packing in the voids to absorb the high frequencies. However, I really don't know how it will sound with a 4 banger.

 

[656of1000]

I fully agree with wanting a quiet, high flowing exhaust. I like the idea of always having that extra power whenever I want it (no cutout for me), but I don't want to have to worry about being hastled for a loud exhaust. Highway drone is a pain, too.

I'm planning a "quiet" 3" exhaust, too. I am hoping that I can find a stock Evo 9 muffler to graft onto the end. I realize that a Evo muffler is probably 2.5" (I'm guessing), but if need be, I can cut off the inlet elbow and weld a 3" elbow onto that plate on the side of the muffler. My thinking is that I'll get a relatively stock sound (for an Evo) and a relatively stock look (being an OE muffler and all).

 

[GreenGSX]

The One Lap VR-4 uses a pretty standard 3" turbo back exhaust with a Magnaflo muffler. To keep the sound level to a livable level we welded in a 24" and 18" resonator which we think keeps the cool guy sound but doesn't beat you up on the road. They were pretty cheap too.

 

[ercp98]

^that is what i did plus a generic twin tip muffler but for 2.5 piping. it keeps the cops around here from noticing me.