[Josh42089]

Have 19 Lt auto. Got rid of the suitcase muffler and put dual magnaflow performance straight through glass packs. 3". Didnt notice it with stock setup but now it feels like when I want to get some quick acceleration that it's bogged down initially. Everything is stock except this. 3" to the y then 2.5 to the mufflers and tips. Anyone else notice that? Is there a way to remedy this or maybe I'm over thinking it. The car when crusing likes to run around 1000 to maybe 1200rpm when at a constant speed in the city.

[Joshinator99]

Is the LT the V6 version? Dual 3” piping would be overkill for a stock V6 for sure. The bigger size will have a penalty on exhaust velocity, so a little drop in the low end torque wouldn’t surprise me.

[Josh42089]

Originally Posted by Joshinator99

Is the LT the V6 version? Dual 3” piping would be overkill for a stock V6 for sure. The bigger size will have a penalty on exhaust velocity, so a little drop in the low end torque wouldn’t surprise me.

No the Lt is the is 4 cyl turbo. Just the glass packs are 3". But from the header back is stock 3" to the y pipe then to 2.5.

[Joshinator99]

Originally Posted by Josh42089

No the Lt is the is 4 cyl turbo. Just the glass packs are 3". But from the header back is stock 3" to the y pipe then to 2.5.

Ok, so stock is 2.5” to each muffler which you moved up to 3”, right?

[Evil-Bee-NH]

Shouldn't have affected anything in a way that would cause it to bog down.

[turbojeep95]

What your noticing the loss of torque at lower rpm's due to the loss of back-pressure from your exhaust modification. I put an exhaust cutout on my car after the down pipe and when running it open, makes a slight drop in performance in the lower rpm range. (torque comes on 200rpm later) Had it dyno'd and the graph verifies the change. Overall, torque output remains relatively the same and horse power will increase slightly at higher rpm's.

[dekes1]

Originally Posted by turbojeep95

What your noticing the loss of torque at lower rpm's due to the loss of back-pressure from your exhaust modification. I put an exhaust cutout on my car after the down pipe and when running it open, makes a slight drop in performance in the lower rpm range. (torque comes on 200rpm later) Had it dyno'd and the graph verifies the change. Overall, torque output remains relatively the same and horse power will increase slightly at higher rpm's.

I know this is one of those car tuning topics that everyone debates, but there's no such thing as exhaust backpressure. What is really in play is the exhaust gas velocity and the scavenging effects of the exiting gas during each exhaust pulse. Exiting gas helps pull in fresh intake air as well as pull out spent exhaust gas.
A larger pipe results in lower velocity which decreases scavenging. End result is lower torque on the low end. But, with a turbo motor, these effects become very minimal since there is a positive charge on the incoming intake air which itself pushes out the exhaust gas. On a turbo motor, one of the best things you can do is open up the exhaust as close to the turbo as possible.

[Josh42089]

Originally Posted by dekes1

I know this is one of those car tuning topics that everyone debates, but there's no such thing as exhaust backpressure. What is really in play is the exhaust gas velocity and the scavenging effects of the exiting gas during each exhaust pulse. Exiting gas helps pull in fresh intake air as well as pull out spent exhaust gas.
A larger pipe results in lower velocity which decreases scavenging. End result is lower torque on the low end. But, with a turbo motor, these effects become very minimal since there is a positive charge on the incoming intake air which itself pushes out the exhaust gas. On a turbo motor, one of the best things you can do is open up the exhaust as close to the turbo as possible.

So what should I do to help with the exhaust mod?hi flow dp or catless, Add an intake for more air? Will all these mods have a balancing affect without having a tune?

[Joshinator99]

Originally Posted by dekes1

I know this is one of those car tuning topics that everyone debates, but there's no such thing as exhaust backpressure. What is really in play is the exhaust gas velocity and the scavenging effects of the exiting gas during each exhaust pulse. Exiting gas helps pull in fresh intake air as well as pull out spent exhaust gas.
A larger pipe results in lower velocity which decreases scavenging. End result is lower torque on the low end. But, with a turbo motor, these effects become very minimal since there is a positive charge on the incoming intake air which itself pushes out the exhaust gas. On a turbo motor, one of the best things you can do is open up the exhaust as close to the turbo as possible.

This. Well said.

[Evil-Bee-NH]

Originally Posted by Josh42089

So what should I do to help with the exhaust mod?hi flow dp or catless, Add an intake for more air? Will all these mods have a balancing affect without having a tune?

You can run all of them without a tune just fine. I did for about just over 16k miles zero issues before i got tuned and zero issues since except a defect part that the manufacturer made good on. You won't need a tune until you choose to tune or get anything more done then the basic bolt-ons you already mentioned

[Josh42089]

Originally Posted by Evil-Bee-NH

You can run all of them without a tune just fine. I did for about just over 16k miles zero issues before i got tuned and zero issues since except a defect part that the manufacturer made good on. You won't need a tune until you choose to tune or get anything more done then the basic bolt-ons you already mentioned

Which tune is most popular/dependable..zzp or Vermont are the ones I've been reading about. Also for the dp id prob go Zzp. Any problems or codes being thrown on these whether hi flow or catless.

[Evil-Bee-NH]

Originally Posted by Josh42089

Which tune is most popular/dependable..zzp or Vermont are the ones I've been reading about. Also for the dp id prob go Zzp. Any problems or codes being thrown on these whether hi flow or catless.

I can't speak for Vermont directly but they are lightyears ahead of what ZZP will give you. Honestly get your own MPVI2 device a cheap $200 laptop and reach oit to vermont tuning. I don't dislike ZZP itself and they will tune you safely same as anyone else cept RPM but the way they make power in a canned tune will limit your power gains. My best advice is find a local dyno tuner or make a trip to vermont tuning they are in northern vermont not far from the Canadian border.

You won't get any codes unless things are installed incorrectly. I installed mine september 2016 drove the shit out of my camaro til i got tuned in late april 2017 and as i said previously zero problems.

Be prepared to invest money in your tune 2017+ is expensive af especially if your an A8.