Magnaflow Muffler + MDS

So you get into manual by pushing to down arrow?

That makes you a lucky man btw right? lol

So you hit it down, and hit 6, which is the gear with a 0.67:1 ratio (top gear lol)

When I hit it down, it says 5, which since we have come to the conclusion that we shift through the same series of manual gears means I am now running the 0.75:1 gear (top gear minus one lol)

So you lucky ******** with 12s can run no MDS and have all your gears while I am forced to lose my top gear... But hey, I can get a tuner so

I have the center console shifter and its just a tap to the left to go to evic #5. This however is actually 4th gear not 5th gear because of the 2' taking the #3 spot. Since the transmisions are the same except for programming, when the '12 trucks are in evic #6 they are actually in 5th gear if we still call 3rd as 2' to compare apples to apples. This should mean then the guys with the 2012 trucks have the ability to use one more gear while in manual mode 6 than the non 2012's in 5.
One thing to note about 2' for non '12s, the truck will shift into 2' on acceleration if the selector is on 3 but skips it if the evic is on 4 and just shifts from 2nd to 3rd gear like in D.

Chaney said:

Man black trucks look good cleaned! For 15 minutes.... I really regret getting black... Except for those 15 sweet sweet sweet clean minutes...

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you are exactly right. i spent saturday washing and cleaning my truck and it looked absolutely amazing. by saturday night it looked like it did before i cleaned it.

Chaney said:

You had two different gear ratios in both trucks. That is exactly what that is. Same thing happened to me going from 3.55s to 4.10s in this truck

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I thought both had 3.55's?

Chaney said:

MDS is garbage and it doesn't give you better gas mileage. Just turn it off and run with it.

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Do you have any proof to this statement? How else would a 5.7 liter v8 get around 18-20 mpg on the highway?

Polaris Pro said:

Do you have any proof to this statement? How else would a 5.7 liter v8 get around 18-20 mpg on the highway?

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Mine gets that with the mds off and the truck running rich

Polaris Pro said:

Do you have any proof to this statement? How else would a 5.7 liter v8 get around 18-20 mpg on the highway?

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Try it out. Like I said earlier, some people see a MPG increase when running in "manual" mode.

Not exactly sure how the MDS works. There are only two real possibilities though, and both of them are ****** so I can see how running W/O it would be better.

Option 1:
Valves, and piston move as normal, but no fuel is added.

Con: piston still has compression stroke eliminating most gains of "disabling" a cylinder, all you do is also eliminate the gain of putting in a tiny bit of fuel, and at least re-cooping the lost work of compressing the air.

Option 2

Piston moves as normal, but valves remain closed at all times by eliminating oil flow to hydraulic lifters.

Cons: Same as above, but there are now two compression strokes, and no explosion stroke, and no fuel. Equally pointless thanks to friction losses.

Option 3 (would serve a purpose but adds significant complexity)
Have separate intake/exhaust port for when cylinder is in MDS operation, allowing the valve to always be open thus no compression stroke ever occurs, and intake/exhaust flow is not disturbed by two cylinders exhausting or intaking simultaneously.

This just shows why MDS serves no real purpose, but to make you feel better lol.

I have a G8 GT with DOD and a full Magnaflow system with X pipe and you can hear it for sure when it kicks in. Some call it drone, but it's really due to the DOD system. A lot of it can be remedied using a capped J pipe or Capped Helmholtz chamber.

It honestly doesn't bother me enough to make any changes and DOD DOES yield me better MPG.

well finally had time to get the 18" magnaflow installed. sounds awesome but drones a little. the only reason this muffler isn't perfect is due to the odd shifting pattern of the transmission, but i'll live with it. next step is xd rockstars. kinda feel like everyone has the rockstars, but i want a totally blacked out truck with a five spoke type wheel. anyone have any wheel suggestions that are all black and five spoke style?

i don't really know what my tranny is... nor do i give a poop, but my 18 inch magna flow on the highway kicks ass, and sounds awesome cruisin' in the city.

I'm thinking when I fill up next, which might not be for another week or so, I'm going to use my SC tuner to turn off the mds system and see what I get mileage wise to be able to determine for myself whether mds is pointless or not. Based on my driving though and how often it's on, I'm expecting to see at least 1 less mpg with mds off. Only time will prove me wrong though.

I have thought about powder-coating my stock 17s to black, not enough time in the day though.

When you guys are turning off the MDS with your tuners does the light still come on? I turned it off w the superchips and today w the Diablo and it the light still comes on

You're eco light will always come on because it comes on whenever the computer believes you are driving in a fuel efficient manner and when MDS is on.