New MAC lightning style catback installed, WOW!!!
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New MAC lightning style catback installed, WOW!!!
I received my new Mac catback at 7:01pm and had it installed and running at 9:40pm. This system is great, very muscular sounding and no interior drone. I even noticed better response of the line. This is what a 300hp engine should sound like. I will post some pics tommorow.
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Junior User
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Mac catback
The Mac sounds muscular at startup and has a deep throaty rumble at take-off and WOT without any drone or interior resonance. I also noticed better acceleration off the line and improved passing power. With the stock exhaust on I was running 50 mph at 1750 rpm, and now with the MAC catback I running 50 mph at 1250 rpm. Don’t know if the mpg has improved since I can’t seem to get my foot off of it, still having too much fun.
2005 f150 Scab 2x4
5.4L
<O
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I've got to raise the B.S. Flag here...there is absolutely no way that your exhaust will change your RPM's at any speed! Your RPM's are predetermined by your transmission, rear gears and your tires. Exhuast has nothing to do with your RPM's and especially a whopping 500 RPM difference.
However, the exhaust looks sweet. Enjoy the sound and additional power.
Schmidtty
However, the exhaust looks sweet. Enjoy the sound and additional power.
Schmidtty
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Joined: Oct 2002
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From: MA
[unscientific opinion]Aftermarket exhaust systems most definately impact rpm levels. With the gases no longer held back, you do not have to "force" (ie higher revs) the gases through the muffler to go faster. No matter what vehicle it has been, or what manufacturer, an aftermarket exhaust kit has always helped in this department.[unscientific opinion done]
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Originally Posted by Schmidtty
I've got to raise the B.S. Flag here...there is absolutely no way that your exhaust will change your RPM's at any speed! Your RPM's are predetermined by your transmission, rear gears and your tires. Exhuast has nothing to do with your RPM's and especially a whopping 500 RPM difference.
However, the exhaust looks sweet. Enjoy the sound and additional power.
Schmidtty
However, the exhaust looks sweet. Enjoy the sound and additional power.
Schmidtty
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Flag is still thrown...
I have a 2005 FX4 5.4L...I have a custom Magnaflow Exhaust (lightning style), FRAMBoost CAI and my favorite modification the EDGE Programmer. I am making way more HP than stock with this set-up and my truck still runs the same RPM's at any given speed that it did when it was bone stock. You might be able to persuade me that a change was of say 40-50 RPM's were seen after some modifications, but 500 RPM's with just an exhaust change??? NOT A CHANCE!
The only way to see a 500 RPM raise or drop is to change the gears in the rear end, or a change to a bigger wheel/tire combo. Come on people!
Schmidtty
I have a 2005 FX4 5.4L...I have a custom Magnaflow Exhaust (lightning style), FRAMBoost CAI and my favorite modification the EDGE Programmer. I am making way more HP than stock with this set-up and my truck still runs the same RPM's at any given speed that it did when it was bone stock. You might be able to persuade me that a change was of say 40-50 RPM's were seen after some modifications, but 500 RPM's with just an exhaust change??? NOT A CHANCE!
The only way to see a 500 RPM raise or drop is to change the gears in the rear end, or a change to a bigger wheel/tire combo. Come on people!
Schmidtty
Fleet Mechanic
Joined: Nov 2004
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From: Pittsburgh, PA
500 rpm drop, no way...you sure you didn't have the overdrive turned off before, and then now you have it on during your 50mph test?
I had the Magnaflow lightning style side exit cat back and did not see a big rpm drop like that.
I had the Magnaflow lightning style side exit cat back and did not see a big rpm drop like that.
I throw the BS flag as well, I've done several exhausts on several vehicles, never seen an RPM drop of any kind.
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Joined: Apr 2006
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From: Escondido, Ca
No mercy...
Assuming you are in Drive at freeway speeds, rpm is a function of rear end gearing, tire size (diameter), converter slippage, and final drive ratio after converter lockup.
HP has nothing to do with it...except for top fuelers/funny cars that spin their slicks so fast that they grow in diameter, thus changing the final drive ratio.
BUT...
At 50 mph, you may not have been locking up your converter...so in theory, the added hp you gained allowed for less throttle to maintain 50 mph, which told the computer to lock up your converter...hence, the 500 rpm change.
Ya think?
Assuming you are in Drive at freeway speeds, rpm is a function of rear end gearing, tire size (diameter), converter slippage, and final drive ratio after converter lockup.
HP has nothing to do with it...except for top fuelers/funny cars that spin their slicks so fast that they grow in diameter, thus changing the final drive ratio.
BUT...
At 50 mph, you may not have been locking up your converter...so in theory, the added hp you gained allowed for less throttle to maintain 50 mph, which told the computer to lock up your converter...hence, the 500 rpm change.
Ya think?
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Originally Posted by The Oldtimer
No mercy...
Assuming you are in Drive at freeway speeds, rpm is a function of rear end gearing, tire size (diameter), converter slippage, and final drive ratio after converter lockup.
HP has nothing to do with it...except for top fuelers/funny cars that spin their slicks so fast that they grow in diameter, thus changing the final drive ratio.
BUT...
At 50 mph, you may not have been locking up your converter...so in theory, the added hp you gained allowed for less throttle to maintain 50 mph, which told the computer to lock up your converter...hence, the 500 rpm change.
Ya think?
Assuming you are in Drive at freeway speeds, rpm is a function of rear end gearing, tire size (diameter), converter slippage, and final drive ratio after converter lockup.
HP has nothing to do with it...except for top fuelers/funny cars that spin their slicks so fast that they grow in diameter, thus changing the final drive ratio.
BUT...
At 50 mph, you may not have been locking up your converter...so in theory, the added hp you gained allowed for less throttle to maintain 50 mph, which told the computer to lock up your converter...hence, the 500 rpm change.
Ya think?
2005 F150 Scab 2x4, 5.4L, 3.55 L.S.
Airaid CAI
Mac Catback
18" MB wheels
BFG 275/65/R18 tires
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Elder User
Joined: Jan 2006
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I'll add that you've got a great-looking setup.
I've got some Magnaflow duals that exit behind the tire and they don't look nearly as nice...just wish I could route them the way you did...not really possible on an Expedition, though, thanks to the frame rail.
I've got some Magnaflow duals that exit behind the tire and they don't look nearly as nice...just wish I could route them the way you did...not really possible on an Expedition, though, thanks to the frame rail.