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Discussion Starter · #1 ·
In the next week or 2 I plan on putting a full exhaust on the srt8. My plan is headers with 2 high flow cats x pipe 2 classic chambered mufflers then straight pipe to two 5" tips. Will I have a loss in Hp due to not enough back pressure with this setup if I go 3 inches the whole way back?
 

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I think you will have loss of HP/TQ on launch with what you describe... Because you need that back .pressure so that you could take off hard.... I have seen quite a few guys complain and go with a custom exhaust only to get rid of it and buy a Corsa exhaust instead at the very end..... I have a Corsa with highflow cats and Love the sound and power at launch....
 

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This sounds similar to the BB exhaust...minus the headers & high flow cats.
Knuckles is right, opening up the exhaust too much on a stock jeep is not the best thing.

Make sure the chambered mufflers you choose will actually help with back pressure...as long as there is back pressure changing from 2.75" to 3" won't matter much.

I have the 3" BB catback with chambered mufflers and X pipe....it a great exhaust.
The Corsa is also a great choice.

If you allow the exhaust to be too free flowing you will lose HP/TQ on a stock engine setup...I wasted a tonne of money testing custom exhaust setups to prove you need back pressure on a stock engine to get the best balance.
 

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Discussion Starter · #4 ·
This sounds similar to the BB exhaust...minus the headers & high flow cats.
Knuckles is right, opening up the exhaust too much on a stock jeep is not the best thing.

Make sure the chambered mufflers you choose will actually help with back pressure...as long as there is back pressure changing from 2.75" to 3" won't matter much.

I have the 3" BB catback with chambered mufflers and X pipe....it a great exhaust.
The Corsa is also a great choice.

If you allow the exhaust to be too free flowing you will lose HP/TQ on a stock engine setup...I wasted a tonne of money testing custom exhaust setups to prove you need back pressure on a stock engine to get the best balance.
Do you have the chambered mufflers along with the Bb mufflers or are te Bb mufflers chambered?
 

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How about the borla S system with no resonators? Would that setup loss power?
 

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Do you have the chambered mufflers along with the Bb mufflers or are te Bb mufflers chambered?
It's the BB catback system with 2 rear BB chambered mufflers....nothing added.
I've never seen a cut away to show the inside of one of these "chambered" mufflers so I don't know what guts are in these things...but it seems to flow well and have a good balance.

I would not say its better than the Corsa, I like the Corsa alot and I only chose BB for the sound...its a lower rumbling sound which I liked better.
 

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How about the borla S system with no resonators? Would that setup loss power?
I would think you would lose "some" low end power with the "S" system, like most aftermarket catbacks, but gain in other higher RPM ranges vs stock for sure...I tested a custom exhaust setup when I was playing around last year that was built like the Borla "S" and it was loud....but thats it...And I did notice a lose of TQ on the ass dyno with having the exhaust this free flowing...thats just my experience though. The best balance I've found so far for what i wanted was the BB

Alot of guys have went fast with different catback exhausts, but I would think its more the supporting mods and tuning rather then the exhaust making an impact here.

Last year my buddy and I went to the track...both jeeps ran exact times with different mods...It was a terrible day for air, both jeeps ran 13s passes....

Mine Jeep - Mopar CAI + Johan Tune
His Jeep - AFE CAI + Johan Tune + Corsa Exhaust

Until you are Supercharged or Turbo charged the "Stock" exhaust is the best for performance, everything else is "noise"and personal taste...IMO...
 

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i dont seem to have drone and doesnt seem like i loss any back pressure with my 2 flowmaster super 44s...except i dont have high flow cats and headers "yet" launch seems better to me. and louder hehehe
 

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Discussion Starter · #10 ·
will i still loose power if i go with 2.5" classic chambered mufflers instead of 3"
 

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i have 3 in mufflers and 3in magnaflow x pipe...i just need new 5' tips...but im not sure im all about going bigger not smaller...but like he said, need some sort of backpressure..to me the super 44s are loudest and new delta flow chambers create some backpressure, just dont lose the cats, no cats, you might as well have straight pipes.
 

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Any power lost down low is more then made up for on the top end. Back pressure is not a factor with this engine as long as you have some kind of X-pipe

My jeep does 1.75 sixty foots with no mufflers or resonators with alot of tire spin still.
 

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i have 3 in mufflers and 3in magnaflow x pipe...i just need new 5' tips...but im not sure im all about going bigger not smaller...but like he said, need some sort of backpressure..to me the super 44s are loudest and new delta flow chambers create some backpressure, just dont lose the cats, no cats, you might as well have straight pipes.
You need to come down and listen to my jeep. Flowmaster mufflers are junk IMO. You will lose power with them!
 

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any power lost down low is more then made up for on the top end. Back pressure is not a factor with this engine as long as you have some kind of x-pipe

my jeep does 1.75 sixty foots with no mufflers or resonators with alot of tire spin still.
you also have a cam + tune....not sure if you are factoring that in...that setup will give you wayyyy more torque down low than a stock setup, so you won't see or feel the loss that much, and that cam is designed for power throughout the rpm range....not comparing apples to apples.

And a 1.75 sixty is nothing to brag about...my stock jeep did that!
 

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And the x-pipe just evens out flow from the engine, its dosent control backpressure....
 

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I would not say NavajoSRT8's "Flowmaster" mufflers / exhaust is junk.

This company seems to be very honest with testing and provides very accurate information to increase buyer knowledge....Check out this link for info and good read...these guys know there stuff, especially with the whole "X" / "H" pipe deal....

Frequently Asked Questions....

http://www.flowmastermufflers.com/index.php?page=40
 

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And the x-pipe just evens out flow from the engine, its dosent control backpressure....
so an x-pipe wont increase torque? maybe you should read flowmasters website again.
 

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so an x-pipe wont increase torque? maybe you should read flowmasters website again.
I think you are missing the original point to this post and...Again you seem to miss the point we are talking pretty much a stock setup, not a highly modified engine or race application....do some more reading and see where they say you will get these TQ gains and on what type of engine...and by no means is the stock 6.1 anything close to a modified / race engine.

Don't mean to hurt your feelings but I'll break it down for you,... "X"-pipe + "free flow exhaust" will give "no" low end HP/TQ gains, it can actually hurt performance and we won't see any better track times with it on "our" rigs, unless you are running a full race application or have a total heads + cam package to move more air...you will only notice performance gains high in the RPM range or the sweet spots on stock engines...you will see this on a dyno if you compare a stock setup VS a free flow exhaust with X pipe, the graph doesn't lie...would you sacrifice 10-20HP/TQ in the low RPM range when you are trying to get this rig (brick) moving to gain maybe 10HP/TQ on the top end???

Get ride of that cam and free up the exhaust with just and x-pipe and straight through mufflers and you will think your jeep shit itself! Your cam + tuning is the reason for your performance improvements and the x-pipe is only helping it out!

Meaning of "Mid-pipe":
The section of tubing between the catalytic converter(s) and the rear muffler on cars that have two parallel exhaust pipes. Performance mid-pipes often have a perpendicular connecting pipe or the pipes temporarily merge. This is to equalize the pressure in both exhaust pipes and keep the engine back-pressure as low as possible since back-pressure is detrimental to high-end power.
H-Style Pipe where there is a perpendicular connecting pipe, resembling the letter H
X-Style Pipe or X-Pipe where the exhaust pipes temporarily merge, resembling the letter X
 

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When BlownWJ and I were down at Johan's being tuned about 2 years ago, Chris did one pull after another. His mods were a Cam, ported intake, 90mm TB, CAI, Headers, no cats I think. He gained 14rwhp with cutouts open vs. closed. Johan was shocked as well at Scott from Billet Tech. He has ALWAYS run faster with them open vs. closed. Now his setup isn't exactly "stock", but it's nothing severe. Still running stock heads. When I was NA, I ran better with mine open vs. closed. Always have.

What some don't realize is the lower part of the "power band" is only used in first gear. First gear rips through so fast that 10hp ain't squat. From that point on..... it's all 4500 and above through out the rest of the run.

Where the cutouts are placed and what type make a difference as well. The low profile ones, unless welded in during a bend, are really just noise makers. We have always run Y-Piped cutouts.

Wait till you throw a turbo on..... then you'll REALLY love the cutouts. We see up to a 40rwhp. increase with it open vs. closed..... but then again, we ain't stock either!;)
 

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Harrison that 40whp increase on open vs closed was that on yours or on Keoni's? Just wondering the difference between a stock bottom end & a fully built motor.

Jim
 
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