Nick93

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I've had my 06 gt for about a month Now, came with pypes muffler deleted axlebacks which sounded nice but wasn't loud enough for me, and i never got any popping on downshifts or decel. So i added a bbk x pipe with high flow cats... car sounds amazing and loud now. But it still does not ever pop or crackle no matter what I do ! Even my 2011 v6 with pypes bombs crackled and popped. Any ideas??
 

dark steed

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My ‘07 GT/CS 5 spd with muffler deletes and stock H/cats popped a good bit on decel, especially when cold. Not so much since I put GTA mufflers on it.
 

tjm73

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Crackels and pops are for rice krispies.

94edab8b9089c46861431dd285ce6193.jpg
 

CammedS197

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Crackling and popping mainly comes to the tune I believe. Its more of whats called lean popping also can happen if too rich if I recall. Basically there is unburnt fuel mixture in the exhaust piping and it detonates on the way out. I could be wrong but I'm pretty sure thats why. I'm cammed and full bolt on and mine doesn't. At least I cant hear it.
 

dark steed

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Mine was stock and popped mostly when cold, I would call it burbling more than popping when it was warmed up
 

o2sys

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It's part of the tune, it's called DFCO (decel fuel cutoff).


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702GT

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stop posting in tech until you understand WTF you're posting about please.

moved.

LOL The giant vein is pulsing! hahaha!


o2sys is correct. Back in the day when my '08 was all full bolt on NA cammed and loud as cherry bombed 350, my tuner had me on a decel fuel cutoff (which really freaked me out to see my wideband swing full lean on decel) and that thing sounded like drive-by with an AK-47. I asked him for something more pleasant, 14.7 all around. No more gangster drive-by. If you want it, and you like it, lean is mean.
 

Pentalab

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I was told years ago the fuel was added on decel.... to cool down the cats a bit after doing a wot pull etc. The unburnt fuel gets burnt up in the blazing hot cats anyway, causing all the racket, so duno if adding fuel is doing anything in the way of cooling down the cats, or anything else. If coasting for a bit in drive, ( 4th).. then manually shift down to 3rd or even 2nd gear, I don't get the racket. But if I give it a bit of gas after coasting 1st, then downshift, then I get the racket, so at least it's controllable. IE: wind it up a bit in 3rd gear, then drop it into 2nd gear.. right at a bus shelter, then scare the shit outa everyone standing there waiting for the next bus. I do that to, if I see that a cop has a ricer pulled over. Then quickly turn the corner so they can't get ur plate number.
 

CammedS197

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Lito made a large post about it on decel. The ecu cuts fuel and spark and the drivetrain is turning the motor (hence you dont need the air fuel and spark to keep it rotating) so your motor is pulling straight air into the motor (hot air or not still cooling since its just ambient air) actually cooling it as well as lubing up the pistons and walls very well since there is no gas in the cylinders to get in the oil that is lubing the walls.

So just air into cylinders and out the exhaust. Email or PM lito for a very well detailed explanation of this and why.
 

travelers

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I was told years ago the fuel was added on decel.... to cool down the cats a bit after doing a wot pull etc. The unburnt fuel gets burnt up in the blazing hot cats anyway, causing all the racket, so duno if adding fuel is doing anything in the way of cooling down the cats, or anything else. If coasting for a bit in drive, ( 4th).. then manually shift down to 3rd or even 2nd gear, I don't get the racket. But if I give it a bit of gas after coasting 1st, then downshift, then I get the racket, so at least it's controllable. IE: wind it up a bit in 3rd gear, then drop it into 2nd gear.. right at a bus shelter, then scare the shit outa everyone standing there waiting for the next bus. I do that to, if I see that a cop has a ricer pulled over. Then quickly turn the corner so they can't get ur plate number.


That sound like the old trick we used to do by turning off the engine in gear and turning it back on. You get a large backfire. Some times splitting the muffler is the only down fall.
 

RocketcarX

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That sound like the old trick we used to do by turning off the engine in gear and turning it back on. You get a large backfire. Some times splitting the muffler is the only down fall.
That was with a carb, it would load the exhaust up with unburnt fuel that was pulled in thru the carb, the boom was it exploding once you had ignition again.
Also a great way to wash the oil out of the cylinders, lol.
 

eighty6gt

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Whatever lito does is great, I loved coasting down near noise walls with my KR mufflers. Now I will be off road with some resonators, mid mounted helmholtz box, and the KR's, should be even better.
 

Pentalab

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Whatever lito does is great, I loved coasting down near noise walls with my KR mufflers. Now I will be off road with some resonators, mid mounted helmholtz box, and the KR's, should be even better.

Those KR's are quiet as a mouse compared to my FRPP FRS-500's. Buddy has identical LT's + hi-flow cats. He has KR's, I have the FRS-500's. Mine is stupid loud vs his ( + I had bad drone around 2 krpm). So in went the pair of pypes M80's, welded in, just b4 the rear axle. We thought for sure he would have to do the same, installing resonator's. (I had mine all done b4 he got started). Nope, his is pretty lame, sounds good, no resonators required with his KR's.
 

WJBertrand

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It's part of the tune, it's called DFCO (decel fuel cutoff).


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I think this is true, though I have a Coyote, it popped and burbled quite a bit on the OEM tune on deceleration. Very noticeable after installing the Borla axle backs. It sounded pretty rowdy actually. Later I added a Ford Racing Pro-Cal tune I was surprised that it now never pops, just a smooth low rumble when slowing.
 

Pentalab

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I hope you're right!!

Local buddy with the same JBA titanium ceramic coated LT's and same JBA catted H midsection (but with no resonator's ), his car is a 2008 GT.. NA, no blower.

Try it 1st. If it's too loud or obnoxious, or drone, it's no big deal to weld in a pair of pypes SS M80's. We cut off the flanges, with the slots in em, at each end of both M80's..... in 3 mins, with the bandsaw. Then welded em 360 degs around the circumference. M80's installed just b4 the rear axle. Or use what ever brand of resonator u want. The SS pypes M80's were cheap at AM, $44.00 each. Still super shiny after several years, zero issues. But they are aprx 4" OD so u want em just b4 the rear axle, which is where you have max ground clearance.
 

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