Slant Six Forum :: Magnaflow muffler install

HardCharger,

The Thrush muffler came off today. It's been fun for the last 3 years!

I finally had the 18" long body, MagnaFlow installed today. What a difference.....no more resonance or vibrations inside the car.

The 18" MagnaFlow gives a whole new meaning to a "free flowing muffler". It has 2.5" internal pipe with 2.25"on the ends.
Pro Exhaust in Auburn next to the airport, installed it for $129. It has a very mellow sound and very quiet up through 65 mph.
Nice power too.....feels like when I took off the stock fan, about a 20Hp increase in the seat of the pants. I also picked up some higher vacuum gauge readings at idle and at cruise.

I may have to retune the carb a little leaner.......the idle jumped a 150 rpm when we backed it out of the shop! It used to idle at 600 rpm in gear, now it's at 750 rpm in gear. I wouldn't have thought the baffles in the Thrush/FLowMaster 40 copy, would have caused that much back pressure.

If you want a quieter free flowing exhaust, try the 18" body MagnaFlow, either the #11265 or the #12255. I couldn't get the 22" #12577 to fit.

It will be interesting to see if the mileage changes too!

Author:	HardCharger [ Sun May 31, 2009 11:15 pm ]
Post subject:
I didn't think that the 4x9 and the 5x8 were much different in sound (assuming straight through not XL) given the same case length. I was under the impression that the only difference was for fitment. :shrug: I have yet to hear from Magnaflow via email on the comparison of the XL and the straight through Mag mufflers for any given case size. I guess I will have to call them...

Author:	HardCharger [ Sun May 31, 2009 11:17 pm ]
Post subject:
I already sent an email off to Doc regarding this idea... Dutra front exhaust manifold, stock rear, 2.0 dual, x pipe, and these mufflers... http://www.magnaflow.com/02product/shop ... in&id=7926

Author:	Aggressive Ted [ Mon Jun 01, 2009 1:41 pm ]
Post subject:
The 5x8x18" case is quieter over the 4x9x18"case do to more absorbing material top and bottom, not just side to side. The quietest config is the corner to corner inlet/outlet do to the longer pipe having more holes exposed and angled absorbtion, not being equal like the straight through versions. You can take all three inlet/outlet versions and look down them to see what I mean.

Author:	HardCharger [ Mon Jun 01, 2009 1:52 pm ]
Post subject:
That makes perfect sense Ted. Thanks

Author:	HardCharger [ Wed Jun 03, 2009 10:32 am ]
Post subject:
So with that in mind Ted something like this should have no drone at all. I don't know if there is that much room under the car for this but assuming it could fit under my 74 Dodge Charger and my muffler guy could pinch the ends down to 2.25... http://www.magnaflow.com/02product/shop ... in&id=7994

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Magnaflow muffler install https://slantsix.org/forum/viewtopic.php?t=15942	Page 2 of 2

Author:	Aggressive Ted [ Wed Jun 03, 2009 1:24 pm ]
Post subject:
HardCharger, Yes! That should do it........hopefully there is enough room. I know on my 74 Dart Swinger I only have room for the 18"version that will tuck up right under the rear seat pocket and still be flush with the frame rails underneath. If I went much longer I would have to let it hang down lower which will collect more snow in the winter.

Author:	Aggressive Ted [ Thu Sep 03, 2009 10:37 pm ]
Post subject:	MagnaFlow Muffler
HardCharger, The Thrush muffler came off today. It's been fun for the last 3 years! I finally had the 18" long body, MagnaFlow installed today. What a difference.....no more resonance or vibrations inside the car. The 18" MagnaFlow gives a whole new meaning to a "free flowing muffler". It has 2.5" internal pipe with 2.25"on the ends. Pro Exhaust in Auburn next to the airport, installed it for $129. It has a very mellow sound and very quiet up through 65 mph. Nice power too.....feels like when I took off the stock fan, about a 20Hp increase in the seat of the pants. I also picked up some higher vacuum gauge readings at idle and at cruise. I may have to retune the carb a little leaner.......the idle jumped a 150 rpm when we backed it out of the shop! It used to idle at 600 rpm in gear, now it's at 750 rpm in gear. I wouldn't have thought the baffles in the Thrush/FLowMaster 40 copy, would have caused that much back pressure. If you want a quieter free flowing exhaust, try the 18" body MagnaFlow, either the #11265 or the #12255. I couldn't get the 22" #12577 to fit. It will be interesting to see if the mileage changes too!

Author:	HardCharger [ Fri Sep 04, 2009 1:03 pm ]
Post subject:	Re: MagnaFlow Muffler
Quote: HardCharger, The Thrush muffler came off today. It's been fun for the last 3 years! I finally had the 18" long body, MagnaFlow installed today. What a difference.....no more resonance or vibrations inside the car. The 18" MagnaFlow gives a whole new meaning to a "free flowing muffler". It has 2.5" internal pipe with 2.25"on the ends. Pro Exhaust in Auburn next to the airport, installed it for $129. It has a very mellow sound and very quiet up through 65 mph. Nice power too.....feels like when I took off the stock fan, about a 20Hp increase in the seat of the pants. I also picked up some higher vacuum gauge readings at idle and at cruise. I may have to retune the carb a little leaner.......the idle jumped a 150 rpm when we backed it out of the shop! It used to idle at 600 rpm in gear, now it's at 750 rpm in gear. I wouldn't have thought the baffles in the Thrush/FLowMaster 40 copy, would have caused that much back pressure. If you want a quieter free flowing exhaust, try the 18" body MagnaFlow, either the #11265 or the #12255. I couldn't get the 22" #12577 to fit. It will be interesting to see if the mileage changes too! That sounds great! I have been busy with college and other stuff lately so I have not had much time for the forums. I got the vinyl top off and I'm doing some temporary POR-15 spot treatment on my car this and next weekend. Should look like a powder blue Jersey cow soon. I plan on getting my tired engine out and on to a stand in the next month or so which should be a fun winter project. I will have to dig up the engine build documents then for sure.

Author:	lindross [ Fri Sep 04, 2009 3:08 pm ]
Post subject:
Great info guys. I'm going to redo mine in the next month or so. After ~20K miles on the car since I got it... the glasspacks have GOT to go. Not pleasant at highway speeds with the windows up for a long trip.

Author:	coconuteater64 [ Thu Sep 10, 2009 6:11 am ]
Post subject:
Quote: Great info guys. I'm going to redo mine in the next month or so. After ~20K miles on the car since I got it... the glasspacks have GOT to go. Not pleasant at highway speeds with the windows up for a long trip. I guess it's all in the brand you use and how you install it. I just got mine back from the shop this morning after a complete "Mulligan" (golf term for do-over) and I can't even hear it idle. Blip the throttle and it sounds more like a Supra than a slant. I'm not using dual exhaust any more, but dual Dutras y'd into a single 2" pipe, back to a single Smithy's glasspack and necks down into 1 7/8" after that. Enough flow to make some power, but realistically sized to provide some backpressure. Smooth, quiet, and enough low end torque to rip the hides right off the rims!

Author:	Aggressive Ted [ Thu Sep 10, 2009 10:15 pm ]
Post subject:
coconuteater64, What ever you can make work to get the results your looking for...... Sounds like a logical setup. I am pretty impressed with is 18" body MagnaFlow. My wife loves it, my son can't believe it........very smooth and quiet and lots of extra power........the stainless steel case and lifetime warranty are kind of nice too!

Author:	coconuteater64 [ Fri Sep 11, 2009 4:18 am ]
Post subject:
Hmmm... me likes lifetime warranty! Stainless steel, affordable price, pretty tempting for my next project (chevy colorado).

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