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Old 04-21-2009, 10:29 AM   #1
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Default Muffler Size

Time for a new muffler. I have been perusing the Magnaflows on Magnaflow Performance | Discount Performance Auto Parts | Performance Exhaust Systems | Flowmaster Performance Mufflers site and trying to decide which size. I'm running a 2 1/2" exhaust.

From the looks of things, it appears that I will be using a 5x8 oval. It is available in 14" and 18" body length, 20 or 24 OAL.

What is the easiest to FIT, center in center out?, offset in/out?

From some photos in other threads, it looks like the 14" body, center in/out would fit well.

I want quiet, though, at cruise. I'm guessing the 18" body will be significantly better in that regard over the 14".

I also am assuming that center in/out has to flow better than offset in/out just because of the golfball test. Do the offset Magnaflows flow as well as center in/out? Are offset good enough and possibly quieter than center in/out when comparing Magnaflow to Magnaflow?

I want to do this right and do it once. The car will eventually end up around 10 PSI.
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Old 04-21-2009, 10:51 AM   #2
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Your original muffler thread has a lot of good info in it. I still think the giant magnaflow <12578> I used is the way to go. And the offset/offset makes it possible. It's a little louder now on full throttle, but still quiet at cruise. Offset/offset has the better flow in my installation since it provides less curve to get into the muffler and back out.
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Old 04-21-2009, 11:11 AM   #3
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GET THE BIG MOTHER.

you'll thank me.

ask braineack. he rode in my car on sat and wouldn't shut up about the exhaust.
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Old 04-21-2009, 11:14 AM   #4
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The offset mufflers will still pass a golf ball. They turn mount the tube diagonally.

Not real sure about the internal construction of the split ones though. (single to dual)
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Old 04-21-2009, 11:23 AM   #5
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Quote:
Originally Posted by m2cupcar View Post
Your original muffler thread has a lot of good info in it. I still think the giant magnaflow <12578> I used is the way to go. And the offset/offset makes it possible. It's a little louder now on full throttle, but still quiet at cruise. Offset/offset has the better flow in my installation since it provides less curve to get into the muffler and back out.
Even with the 2 1/2" exhaust, transition it up to the 3" unit?
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Old 04-21-2009, 11:34 AM   #6
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Yes. Or why not? IF you ever decided to go up on the exhaust size pre muff you'd have the muff to match. And it's not going to hurt to have it larger. Besides, we already know the 3" is hush with a full 3" exhaust.
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Old 04-21-2009, 11:39 AM   #7
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The offset mufflers will still pass a golf ball. They turn mount the tube diagonally.

Not real sure about the internal construction of the split ones though. (single to dual)
Mine is 3" center in, offset out. And it will pass the golf ball test.
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Old 04-21-2009, 11:42 AM   #8
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OK, I'm convinced. Ordering MAGNAFLOW MUFFLER 6" X 12" 22" BODY 3" O/O 12578 today. Maybe it will smooth out my jumpy MAP pressures at the upper RPMs. Magna thought it could be from excessive backpressure and it is distinctly possible with the old Flowmaster.
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Old 04-21-2009, 11:42 AM   #9
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Quote:
Originally Posted by y8s View Post
ask braineack. he rode in my car on sat and wouldn't shut up about the exhaust.
amongst other things...

Quote:
Originally Posted by Stein View Post
Even with the 2 1/2" exhaust, transition it up to the 3" unit?
get the same in 2.5".
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Old 04-21-2009, 11:57 AM   #10
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you might need to upgrade the mid pipe while yer in there. wink wink.
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Old 04-21-2009, 01:51 PM   #11
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My magnaflows are center/offset to match up with the entry and exit bends better. Also I went with resonated tips to help keep her quiet under cruise. Works like a champ; sounds awesome at heavy loads but under cruise isn't loud and doesn't drone.
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Old 04-21-2009, 06:02 PM   #12
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I went from a flowmaster type muffler to a cheap POS turbo style muffler and got improved flow (quicker spool). Word is that the chambered mufflers are bad for turbo'd cars.

FWIW - Enthuza (the original owner) was stepping up their muffs a 1/2" in diameter from the preceding pipe dia. because it showed better spool on the dyno (and better sound at the exhaust).
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Old 04-21-2009, 06:06 PM   #13
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Quote:
Originally Posted by m2cupcar View Post
FWIW - Enthuza (the original owner) was stepping up their muffs a 1/2" in diameter from the preceding pipe dia. because it showed better spool on the dyno (and better sound at the exhaust).
Cool. I should be good to go. One 2 1/2" 180 SS mandrel bend, one 3" 90 SS mandrel bend and a 2.5">3" transition almost = price of muffler FTL...
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Old 04-21-2009, 06:11 PM   #14
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Quote:
Originally Posted by Ben View Post
Also I went with resonated tips to help keep her quiet under cruise. Works like a champ; sounds awesome at heavy loads but under cruise isn't loud and doesn't drone.
What did you use? I have been thinking about doing that very thing but have not found any resonated tips yet, that I like, that are small enough to fit. 3" inlet, short body length.
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Old 04-21-2009, 06:58 PM   #15
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Quote:
Originally Posted by Chris Swearingen View Post
Mine is 3" center in, offset out. And it will pass the golf ball test.
One of these numbers?
Name:  mufflerstraightthrough.jpg
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Mine is for a car making at least 300 at the wheels though..I'm not sure anything more than 2.75" is necessary for most MT setups.

Either way, bigger is better for case size. Magnaflows are all straight through so they flow nice, IMO they sound the best, and a bigger case should muffle more.

Last edited by Orion ZyGarian; 04-22-2009 at 12:00 AM.
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Old 04-21-2009, 08:40 PM   #16
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ansa silverline > *
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Old 04-22-2009, 12:16 AM   #17
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Thanks. I looked at the Silverline stuff this evening, also Monza. I did not see anything with a 3" inlet, resonated, that would work lengthwise.
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Old 04-22-2009, 08:52 AM   #18
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Quote:
Originally Posted by ZX-Tex View Post
Thanks. I looked at the Silverline stuff this evening, also Monza. I did not see anything with a 3" inlet, resonated, that would work lengthwise.
I have one from my 3" enthuza package. I know 2 others with 3" and a big Magnaflow and they wish they had my muffler. It sounds similar to the mrz-r motor

I'll make a vid of my car for you this weekend.
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Old 04-22-2009, 11:10 AM   #19
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Hustler just to be sure are you talking resonator tips or mufflers? I'm looking for a tip I could add to the existing system to make it a little quieter.
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Old 04-22-2009, 08:14 PM   #20
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How much do resonated tips actually do anyways? I always thought they were just expensive flashy add-ons.
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