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Discussion Starter · #1 ·
I have a 2016DCT VT.

TL:DR. I gutted my 845 hi flow cat and lost my pops and bangs

I will try and keep this short as I tend to go on for awhile while overthinking but I have had a few different tunes in the past (eurocharge custom, BTRcc, and now I have SXTH. With BTR I had AK47 like bangs pretty much on demand but the car wasn't running right file after file. I somehow talked myself in to wanting to get a catless downpipe and Kyle from 845 suggested that I just gut my hi flow instead, it would be the same thing without having to spend the money again. After de-gutting I made sure everything was clean and everything was running correctly. I have no lights on the dash and somehow I don't have any pops. I switched to SXTH tune shortly after and we've been trying to get my pops back but can only get these quick and quiet pops when letting off the gas in sport mode at about 4500rpm. The cat housing is the only difference between 845' catted and catless. Could this really be the issue? Has anyone gutted their hi flow before and experienced this?

Edit: The shop that installed my dp cross threaded a bolt into the turbo housing and can't be removed without damaging turbo (they didn't end up charging me for the job)

Current performance mods:

SXTH tune,
ISR Race Exhaust,
845 IC with HKS BOV
HKS MK45XL cold plugs,
dual catch cans,
steel braided fuel line,
Turbosocks 3.5inch BeastMode Intake
845 gutted 3 inch downpipe
Mac Bov solenoid
Mac Wastegate Solenoid
 

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Administrator
2015 auto VT, 2013 manual VT × 2
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5,429 Posts
Tune will control pops n bangs on your setup nothing else.
 

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2016 Hyundai Veloster Rally Edition
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6 Posts
Hey man, I'm stage 2 straight piped from the downpipe (hoping to swap to a 4in free flow downpipe soon) and I have pops and bangs. Sounds like the rally cars you see on youtube videos. Get a burble tune bro, so worth it and fairly inexpensive.
 

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Premium Member
2016 Veloster Turbo DCT w/ Tech Package
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127 Posts
You removed the hottest part of the exhaust. If there isn't a portion of the exhaust that gets hot enough, the unburnt fuel will blow out the tailpipe without backfiring.. er.. "pops and bangs". If you keep running like that then you'll probably end up with carbon deposits in the exhaust and start getting "pops and bangs" just like an old-school Impala or Oldsmobile. :LOL:
I remember when people collectively laughed at backfiring cars. Now it's a "feature" and my car is basically a "sleeper" because it doesn't have pops and bangs to advertise it is modded.
I digress; I suppose you could probably wrap the downpipe very well with exhaust insulation wrap to to preserve heat in that portion of the pipe and possibly get your pops and bangs back.

Removing the high flow CAT probably didn't accomplish anything.
Any HP gain from completely removing a CAT from a small engine is likely countered by the reduction in helpful backpressure.
 

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Administrator
2015 auto VT, 2013 manual VT × 2
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5,429 Posts
You removed the hottest part of the exhaust. If there isn't a portion of the exhaust that gets hot enough, the unburnt fuel will blow out the tailpipe without backfiring.. er.. "pops and bangs". If you keep running like that then you'll probably end up with carbon deposits in the exhaust and start getting "pops and bangs" just like an old-school Impala or Oldsmobile. :LOL:
I remember when people collectively laughed at backfiring cars. Now it's a "feature" and my car is basically a "sleeper" because it doesn't have pops and bangs to advertise it is modded.
I digress; I suppose you could probably wrap the downpipe very well with exhaust insulation wrap to to preserve heat in that portion of the pipe and possibly get your pops and bangs back.

Removing the high flow CAT probably didn't accomplish anything.
Any HP gain from completely removing a CAT from a small engine is likely countered by the reduction in helpful backpressure.
Pops and bangs can be helped or hurt by heat in the exhaust side but the actual fuel burn to make the sound is initiated by the spark plug. You can easily get pops n bangs on a car with full exhaust or with a catless DP and no exhaust. So relies on the tune more than anything else in this case.

Backpressure has no benefits in these engines at all.
 

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Premium Member
2016 Veloster Turbo DCT w/ Tech Package
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127 Posts
Backpressure has no benefits in these engines at all.
Damn, enough with the conjecture! Everywhere on this forum..
Didn't you also say these cars just have sooty exhaust?
Eliminating backpressure will result in reduction in exhaust flow and inability to scavenge.
I'll defer to your experience on the artificial backfires, but you are simply wrong about backpressure having no benefit.


Note: This is not to say that you don't want to reduce backpressure at all. Reduction in backpressure is helpful to a point, but beyond that point you are hurting performance, polluting, and accumulating carbon deposits in your cylinders, on your valves, and in your exhaust. Backpressure is a spectrum, not a True or False.
 

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2016 Veloster Turbo DCT Ultimate
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283 Posts
Damn, enough with the conjecture! Everywhere on this forum..
Didn't you also say these cars just have sooty exhaust?
Eliminating backpressure will result in reduction in exhaust flow and inability to scavenge.
I'll defer to your experience on the artificial backfires, but you are simply wrong about backpressure having no benefit.


Note: This is not to say that you don't want to reduce backpressure at all. Reduction in backpressure is helpful to a point, but beyond that point you are hurting performance, polluting, and accumulating carbon deposits in your cylinders, on your valves, and in your exhaust. Backpressure is a spectrum, not a True or False.
I get the talk about back pressure in NA applications. But in FI, unless you're talking about exhaust manifold design, everything post turbo should be as freeflowing as possible. As to not choke up the wastegate and sap the car of power. All scavenging happens between the engine and the turbo unless I've got it misunderstood.
 

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Premium Member
2016 Veloster Turbo DCT w/ Tech Package
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127 Posts
Sorry, I apparently derailed the conversation from the OP. I'll see myself out.
 
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