Installed New Cat-Back Exhaust

[speedybenz]

I had a Cat-Back exhaust system installed today. I t uses a Magnaflow model 12468 muffler where the stock resonator went and then dual 2.5" diameter pipes to the rear bumper. I had two crappy polished tips put on ofr now until I get a chance to check out the system and maybe make some changes.

The Magnaflow muffler is a 2.5" diameter dual in and dual out. The center of the muffler has the two inside pipes met up into one bigger chamber like a big X-pipe.

One draw back is the pipe bends are not mandel bent so that is not as good as it could be. But now I have a good working pattern to redue the pipe with mandel bent tubing.

The exhaust still flows much better than the AMG system It replaced and it's some 40 lbs lighter. The sound is very nice except for a slight resonance at 1800-2200 rpm.

May next task will be to find out what it will take to get rid of the resonance.

THe ECU is still learning the difference in the performance of the new pipe so I am waiting for the performance to catch up.

Jeff

[Denlasoul]

What are the flow rates for the stock exhaust and the Magnaflow?

[714guy]

Glad to hear you got it in. Jeff do mandrel bends help out a lot?? would removing stock resinator do anything, i ve wanting to this but afraid it might me to loud.

[speedybenz]

714,

Mandrel bends do help out. If you had a 2.5" diameter pipe and bend it with normal press type benders the inside pipe diameter gets reduced to say 21/4" instead of the 2.5". So you lose some flow. If you only needed 2.5" piping and went to 3" piping and used the press benders you would be fine even though you lost some pipe diameter. But a 3" pipe weighs more.

And no you do not need the stock resonator. Many people have removed it and reported only very slight increases in noise.

Denlasoul,

I tried to get the flow rates out of Magnaflow and AMG, buty they claim they do not have that info. I can only guess that the Magnaflow muffler flows more as it is a straight through design and merges the two pipes together in the center and then smoothly separtes flow again at the exit. Sort of a muffled "X" pipe.

Jeff

[Under Pressure]

How come you got crimp bent instead of mandrel bent?

[speedybenz]

I got the crush bends not by choice. I could not find anyone to build me an exhaust system that really knows what they were doing.

And at this point I am not real happy with the quality. It is not up to my standards or that of an AMG Mercedes. So I will most likely get it redone.

Jeff

[speedybenz]

http://speedybenz.home.comcast.net/DSC00558.JPG

Today I checked the back pressure of the new exhaust by drilling a hole before the muffler and then putting a fitting into the hole and attaching an air pressure gage.

Runing the car through the gears to redline showed a maxium of 1 psi of back pressure. I was hoping for 1/2 psi or less, but 1 psi isn't too bad.

Now I will have to check what it is before the first cat and the 2nd cat.

Jeff