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Discussion Starter · #1 ·
Opinions on Magnaflow

I would like to put a magnaflow system on my 73' GT. Not just the muffler, but the whole system. Anyone else done this? How does it sound, and what size pipe did you use? Sounds clips woud be awesome. If nobody has sound clips, what vehicle could I compare the sound to? I could do a search for Magnaflow on other vehicles to see how it may sound. Thanks

Jon
73' GT
 

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There is no Magnaflow system made for Opels, you'll have to make your own. The Magnaflow mufflers sound good however, and they make good power. In fact that's all I use now. Tubing diameter is dependent on the engine size and the modifications you've done to it.....larger diameter tubing will tend to be louder, and the smaller the muffler...the louder it is. Generally, if you have a single carburetor and a 1.9 or 2.0 litre, stick with 2" diameter exhaust pipe. It'll handle 140-150 hp and will have very strong torque. The biggest problem with a GT is fitting two mufflers under the car...there's not a lot of room there!

I'm currently building an all stainless exhaust for an Opel rally engine, and it's using two stainless Magnaflow mufflers and 2.25" stainless tubing. But this engine is a 2.0 litre with 10.8:1 compression, a fully ported head, healthy solid lifter cam, twin 45 DCOE Webers, and a custom equal length header. Plus the engine will spend all it's time between 4500-7500 rpms. If it was for street use I'd probably still use 2" tubing.

Bob
 

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Discussion Starter · #3 ·
I will probably use a 2" tube...2 1/4 at the most. I am probably going to tell the muffler shop what I want the sound to be like, and that I probably want Magnaflow..and they should be able to customize something for me. No matter what I go with, I am getting all new tube bent and stuff..so finding a spot to fit it isnt a problem. With the magnaflow muffler and cat, do you get more of a rumble or more of a whine like you would get from a Ricer? I kinda want a mixture between the 2. Power don't matter too much..although more is better.
 

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would the ''cat" be referring to a catilytic converter? if so are you adding one, and why?
 

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A cast iron, single-cam, 8-valve Opel engine will never sound like a 'ricer' engine, the acoustics are entirely different. They tend to have their own unique sound, not 'ricey', and not musclecar-like, but nice just the same. If you have a hot cam and compression, it sounds pretty sweet.
 

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Discussion Starter · #6 ·
Jordan, yes I did mean Catalitic Converter, and I don't think I am putting one on..although I was kind of worried about having all pipe with only a muffler..how loud would that be? Does anyone have sound clips?
 

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Detritus Maximus
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I have a 2nd gen (87) non-turbo RX7 and they can be very raspy/tinny, especially when I had a gutted cat and a pipe replacing the two pre-cats (the car had three cats originally). I replaced the gutted cat and pipe with a Bonez Superflo Cat. Dramatically changed the tone of the exhaust. Much deeper. I was also running a Racing Beat y-pipe (very thick wall tubing) and stock-type RX7 Bosal mufflers, nothing exotic.

I would say if you want a deeper sound and a cat, the Bonez might be a good choice in place of one of the two mufflers Bob recommends. The Bonez Superflo did wonders for my emissions on the rotary, and is a reasonably good flowing cat, but they aren't cheap, figure about $300, but they are nicely made and will do what you want. Check them out at Rotary Performance. The cats are available with a pre-silencer (like mine) or as just a cat to be fitted into an existing application.
 

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you heard my car here at the house jon, its just a header, stock size piping with a stock rear resignator, the front muffler has been eliminated. there is a sound clip on here also. in my own opinion it sounds really good, hard to describe its sound
 

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I just finished installing a new exhaust system using 2-inch mandrel bent pipe from the junction of the two down pipes on the headpipe to a MagnaFlow 4 x 9 oval, part number 11365. From the muffler I ran 2 1/2-inch mandrel bent pipe over the axle to a 2-inch "U" capped off by two Monza Pace setter resonators. The system is loud but not unbearably so. It has a nice throaty sporty sound very similar to my HI-PO 289 with headers and dual exhaust just not as loud. I ran the car for about a week without the resonators and it was too loud and "bubbly". The resonators smoothed the and lowered the tone considerably. The muffler was a tight fit but it did fit with a little rubbing from the emergency brake cable but it does not hang down low. I will try to get a sound bite and post it.

hth
Brian
 

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Discussion Starter · #10 ·
bq97, please do! Is that on a GT with a stock engine? I am leaning towards 2" pipe with 2 1/4 over the rear axle. Probably a 4" round muffler right before the axle, so maybe I could possibly even do a 2" in and 2 1/4" out. I want more of the Import Tuner sound, then a Hot Rod or muscle car. Not really ricey, just like the sound that would be on a Mustang or something. A little bit of a rumble, but nothing that sounds like a V8.
 

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Sparky37, The engine is a 2.0L with a Isky O-66 cam, sprint exhaust manifold, intake ported to RallyBob's Torquer/Hot-Street Combo specs but welded, no epoxy, Weber 38 DGES, Crane XR-700 ignition and a cold air setup with K&N filter and a Weber Air remote air cleaner adapter, model # 3-0090.

As a side note the air cleaner adapter seemed to flow like crap until I made some major modifications to it. I raised the base of the adapter up even with the top of the carb top plate using a portion of Redline-Weber Air Filter Adaptor # 99004.350 and cut out the front post and 1/2 the top cover bolt down cross bar off the bottom plate (it sat right in line with the small opening). Then I cut the 2 1/2 inch oval off the domed portion and welded on a 3 inch OD aluminum pipe that I squashed down into an oval and trimmed to mate to the contours of the domed portion. After these mods to the adapter the engine seems to have better low end torque and gets up to speed a lot quicker. As opelenvy said in his product review of the adapter as it comes is restrictive. Right now I'm using flex tubing from the filter to the carb but I have a 3 inch piece of mandrel bent pipe getting powder coated to match the exterior color so I'll replace the flex tubing with that for some extra show when needed.

The Car runs great with this setup. The looks combined with the exhaust note seems to be a bit intimidating to the ricer and Mustang GT crowd. They are not sure what an Opel GT is or what the hump in the hood is for, most think a V8 or some high dollar euro engine lurks under the hood and are suprised to see a 4 banger with a carb!

Brian

Brian
 

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Sparky73 said:
Probably a 4" round muffler right before the axle,

I think you will find this is very loud for road use. Travis, I believe you ran the same 4" round, 2" inlet Magnaflow in your race car?

Bob
 

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Pathologic Opeler
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pacesetter resonators

Bq97 ..Which Pacesetter resonator did you use?...Did you use 2 duals or a pair of Pencil tips?

I need to attenuate my exhaust a bit and I want to add pacesetters.
 

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RallyBob said:
Travis, I believe you ran the same 4" round, 2" inlet Magnaflow in your race car?
I started with a 4" round Magnaflow with 2-1/2" core and it was loud, much like the cherry bomb I had on previously, but better tone. I then added an additional 4" round with 2-1/2" core which helped alot, but still isn't quiet. The car had both mufflers on it when you raced it at Devens, BTW.

I performed a few sound tests with a sound meter after the neighbors called the cops one afternoon about the noise during jetting of the carb. I found that with two mufflers and the motor at 3000rpm, the car was slightly quieter at my property line than my skill saw(roughly 150 ft from the car).

-Travis
 

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Travis said:
I performed a few sound tests with a sound meter after the neighbors called the cops one afternoon about the noise during jetting of the carb. I found that with two mufflers and the motor at 3000rpm, the car was slightly quieter at my property line than my skill saw(roughly 150 ft from the car).

-Travis
Did you ever do an SCCA-style sound test, and if so what were the results? Was was the db level with your property line test? I believe the federal standards are 95 db, which is still pretty darn loud for a street car...
 

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I used a 2" pipe from the Y and back with two Magnaflow mufflers. Hit a search on the forum here and you should find a link to the MP3 I made of mine on the Manta. I also have posted the stock numbers for both of these.

Many thanks to RallyBob for the assistance in choosing the right ones.

Its a Manta, so your mileage might vary a little on exact numbers here.

Ohh, mine are straights. :)
 
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