[Menesesjesse]

I always wonder why people want to remove cats. The engineers spent hundreds of hours getting the right flow and exhaust note and then we yank it thinking we will do better. In reality 20hp would be barely noticible in this car. Good cats tend to be less restrictive than the mufflers. We are not in the 70's where the cat would choke the motor. Your better off dealing with the tires than the engine. Overhead valve motors need back pressure to run right and to keep the torque numbers up. The computer connects the dots to make sure the right mixture is there for all this to happen. Open exhaust is fine if you just want to track it but creates more problems with drivability. I always tell people that for every action there is a reaction. I would suggest that unless you are an engineer I would shy away from these mods and stick with improving times with tires or even a future mapping of the computer when that comes out.

 

[Blackdevil77]

I always wonder why people want to remove cats. The engineers spent hundreds of hours getting the right flow and exhaust note and then we yank it thinking we will do better. In reality 20hp would be barely noticible in this car. Good cats tend to be less restrictive than the mufflers. We are not in the 70's where the cat would choke the motor. Your better off dealing with the tires than the engine. Overhead valve motors need back pressure to run right and to keep the torque numbers up. The computer connects the dots to make sure the right mixture is there for all this to happen. Open exhaust is fine if you just want to track it but creates more problems with drivability. I always tell people that for every action there is a reaction. I would suggest that unless you are an engineer I would shy away from these mods and stick with improving times with tires or even a future mapping of the computer when that comes out.

You are absolutely right. Sometimes the engineers have to hold back some power in order to meet emissions. That's how I think a lot of people are gonna try and squeeze out some more power out of these cars. In the meantime, nothing can really be properly done until the ECM is cracked and the proper adjustments can be made to whatever parts someone might want to add or change on the car. First step is cracking that ECM.

 

[Top Cat]

We had a meeting with the SRT engineer's a few years back in Ohio, they had come to a racing event and had taken the time to watch ask questions and take a few questions, the exhaust of the SRT was one topic that was brought up, the engineers couldn't quite understand why most people changed the exhaust as one of the first mods and even were somewhat tweaked, but it looks as if they were listening with the Hellcat lineup.

 

[Blackdevil77]

We had a meeting with the SRT engineer's a few years back in Ohio, they had come to a racing event and had taken the time to watch ask questions and take a few questions, the exhaust of the SRT was one topic that was brought up, the engineers couldn't quite understand why most people changed the exhaust as one of the first mods and even were somewhat tweaked, but it looks as if they were listening with the Hellcat lineup.

On the Hellcat, I highly doubt I would touch the exhaust. I still haven't heard it in person but based on the videos, the sound is absolute perfection! And the fact that people are saying it's much louder than the stock Shelby exhaust really makes me want to leave it alone. I'd just like to do a few tweaks to get some more juice out of it. My goal for the car would be to trap 130+ in the quarter mile. From the tests we've seen, that doesn't seem like it would be that hard at all.

 

[Texhellcat]

From the looks of these Hellcat manifolds aftermarket headers has to help flow and power. I've never seen where a header looses power. Sure boost will drop but volume of flow increases. I think we are going to be surprised when somebody installs the first set of headers.

 

[Next Phase]

From the looks of these Hellcat manifolds aftermarket headers has to help flow and power. I've never seen where a header looses power. Sure boost will drop but volume of flow increases. I think we are going to be surprised when somebody installed the first set of headers.

I hope you're right... As I know this car will sound amazing with some headers.

I've seen first hand that headers on a boosted car drops boost by 1 to 1.5 lbs. I'm not sure how much back pressure you'll lose as I don't know how restrictive the stock set up is.

It may not lose much peak power since a stock HC runs 11.6 lbs of boost. My Vette was running 6 lbs...and I lost 1 lb of boost ; droopped my peak numbers, but I gained power under the curve and the tq went up. (From memory, my peak numbers at that time dropped by 12 or so...tq went up by 30.)

 

[Texhellcat]

And look at the large intake ports on these heads. If the exhaust ports are proportional then that manifold is restrictive. Assuming the cam isn't the limitation. Will be interesting to see a dyno before and after headers but with tuned before and after as well. Without a tune headers might lean it out too much a create knock retard.

 

[Blackdevil77]

I hope you're right... As I know this car will sound amazing with some headers.

I've seen first hand that headers on a boosted car drops boost by 1 to 1.5 lbs. I'm not sure how much back pressure you'll lose as I don't know how restrictive the stock set up is.

It may not lose much peak power since a stock HC runs 11.6 lbs of boost. My Vette was running 6 lbs...and I lost 1 lb of boost ; droopped my peak numbers, but I gained power under the curve and the tq went up. (From memory, my peak numbers at that time dropped by 12 or so...tq went up by 30.)

In my past experiences, headers and better flowing exhaust does decrease visible boost pressure, but I've never seen a resulting drop in actual power because of it. I've always seen the opposite. Boost pressure is just a measure of restriction. With proper tuning, this should be beneficial.

I'm new to Mopar so I really have no idea, but maybe those of you Mopar guys have a better idea/guess than me. When do you think the ECM will be cracked? How long does it usually take? I don't remember tuners having such a hard time cracking the ECM on GM or Ford vehicles.

 

[BrightWhite392]

And look at the large intake ports on these heads. If the exhaust ports are proportional then that manifold is restrictive. Assuming the cam isn't the limitation. Will be interesting to see a dyno before and after headers but with tuned before and after as well. Without a tune headers might lean it out too much a create knock retard.

Header Fitment,
Running LT headers on my Challenger SRT8 6.4, would my headers be applicable for the Challenger HC?
Would like to upgrade to the HC, thoughts are to keep my 392 LT headers,O/R mid, and aFE SS 3'' for the HC.
The HC exhaust ports do look be opened up,compared to the 392.
Thank You for any help

 

[Bossnova3]

In my past experiences, headers and better flowing exhaust does decrease visible boost pressure, but I've never seen a resulting drop in actual power because of it. I've always seen the opposite. Boost pressure is just a measure of restriction. With proper tuning, this should be beneficial.

I'm new to Mopar so I really have no idea, but maybe those of you Mopar guys have a better idea/guess than me. When do you think the ECM will be cracked? How long does it usually take? I don't remember tuners having such a hard time cracking the ECM on GM or Ford vehicles.

I'm completely with this statement on my GT500 as soon as I installed headers I gained 38rwhp and 69rwtq and lost about 1.5lbs of boost, again the less restrictive the system the better eventhough I do agree that the HC has an amazing sounding exhaust I think that headers will make it that much sweeter while adding power let's see just need ECM cracked and hold on

 

[Blackdevil77]

I'm completely with this statement on my GT500 as soon as I installed headers I gained 38rwhp and 69rwtq and lost about 1.5lbs of boost, again the less restrictive the system the better eventhough I do agree that the HC has an amazing sounding exhaust I think that headers will make it that much sweeter while adding power let's see just need ECM cracked and hold on

That's about as good as it gets right there, very nice gains. X pipe? H pipe? What year GT500?

 

[Badass69]

I'm completely with this statement on my GT500 as soon as I installed headers I gained 38rwhp and 69rwtq and lost about 1.5lbs of boost, again the less restrictive the system the better eventhough I do agree that the HC has an amazing sounding exhaust I think that headers will make it that much sweeter while adding power let's see just need ECM cracked and hold on

Bingo..... I laugh a little when guys see that boost numbers dropped with headers so they must have lost power........ no you just made the system less restrictive and in turn more efficient. An engine also is not like the water system we have on our steam generators where we require actual "backpressure" to restrict water flow. I really dislike the term as people don't understand it. You want the flow path efficient and preferably the lowest level of restriction possible while still allowing the exhaust to scavenge. Realistically you can you the spent gases in the exhaust to almost act a venturi and draw the exhaust past the exhaust valve. On a boosted engine...... well it's still critical to overall drivability.

Long tubes for these cars should provide some decent gains. I don't like aftermarket high flow cats and as we have no laws here against it I just choose to not use them.

 

[Bossnova3]

That's about as good as it gets right there, very nice gains. X pipe? H pipe? What year GT500?

08 GT500 with a custom 3" exhaust and H pipe

 

[mudrayneracing]

Bingo..... I laugh a little when guys see that boost numbers dropped with headers so they must have lost power........ no you just made the system less restrictive and in turn more efficient. An engine also is not like the water system we have on our steam generators where we require actual "backpressure" to restrict water flow. I really dislike the term as people don't understand it. You want the flow path efficient and preferably the lowest level of restriction possible while still allowing the exhaust to scavenge. Realistically you can you the spent gases in the exhaust to almost act a venturi and draw the exhaust past the exhaust valve. On a boosted engine...... well it's still critical to overall drivability.

Long tubes for these cars should provide some decent gains. I don't like aftermarket high flow cats and as we have no laws here against it I just choose to not use them.

so i have a boost question, if the hellcat is electronic boost controlled allowing it to make X boost and bypassing to exhaust the excess when you open the exhaust why would it reduce the boost since it is fully capable of making more with the limiter allowing it? wouldnt backpressure be less critical on this type of setup as oposed to a turbo which would loose boost or a supercharger that just was to small to make more?

 

[Best Vapor]

Been awhile here so headers with pulley and tune make more power or is verdict still a no go