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12-15-2006, 07:11 PM
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Hummer Professional
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Join Date: Jul 2005
Location: New Jersey
Posts: 255
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Exhaust?
2005 H2 I presently have borla headers and borla catback.
Is there anything I can do to the cats?
Is a high air flo cat available?
I'm in NJ and they must be seen. Beside with the computer and stuff, I really don't want to exclude them.
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12-16-2006, 02:57 AM
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Hummer Guru
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Join Date: Oct 2005
Location: Charlotte, NC
Posts: 2,767
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Re: Exhaust?
Is there really a big difference that would justify messin' with the cats? I honestly don't remember ever seeing any performance gains by removing normally operating cats.
Just wondering.... hate to see you spend a bunch of extra money for no benefit.
Mark
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12-16-2006, 03:32 AM
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Hummer Authority
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Join Date: Sep 2005
Location: Texas
Posts: 1,795
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Re: Exhaust?
I think you'd be better off getting custom mapping done on your ECM. If you don't have it already, it's probably running too lean with what you have there.
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12-16-2006, 11:44 AM
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Hummer Professional
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Join Date: Aug 2005
Posts: 258
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Re: Exhaust?
I have modified my cats with sports steel cats.
The difference is very big and the test about exhaust gas is ok for the law.
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12-16-2006, 01:50 PM
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Hummer Professional
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Join Date: Jul 2005
Location: New Jersey
Posts: 255
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Re: Exhaust?
Quote:
Originally Posted by Ernie Italy
I have modified my cats with sports steel cats.
The difference is very big and the test about exhaust gas is ok for the law.
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Ernie, very interested in this Turmax....is it available in th US. All my searches come up in Italian.
Do these effect the sound?
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12-16-2006, 01:54 PM
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Hummer Professional
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Join Date: Jul 2005
Location: New Jersey
Posts: 255
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Re: Exhaust?
Quote:
Originally Posted by tomp
I think you'd be better off getting custom mapping done on your ECM. If you don't have it already, it's probably running too lean with what you have there.
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Custom mapping has been done already......i just feel the motor is taking in LOTS of air and not leaving fast enough.
I am also hoping to richin the sound up a little more. Don't get me wrong...the borla sound awful sweet....maybe one or two octives will satisfy me. ARE WE EVER SATISFIED? DO WE EVER GET ENOUGH?
Prolly not!!!!!!!
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12-16-2006, 02:32 PM
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Hummer Professional
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Join Date: Aug 2005
Posts: 258
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Re: Exhaust?
Quote:
Originally Posted by HUM GOOD
Ernie, very interested in this Turmax....is it available in th US. All my searches come up in Italian.
Do these effect the sound?
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A little bit...the sound is more breathe and "open". Not loud... I like it
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12-16-2006, 06:00 PM
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Hummer Authority
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Join Date: Sep 2005
Location: Texas
Posts: 1,795
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Re: Exhaust?
Anytime you open up the exhuast flow, you drop back pressure which is going to reduce your low end performance. It's a trade-off
Most exaust companies focus on wide-open performance numbers and not on the low-end. I ended up trashing my first exhaust system to go with one that had better low-end performance.
Also, it may be a good idea to swap out the MAF sensor for one that can meter the air better. The OEM unit can only meter within a certain range of air and you may be outside of that range if you have not changed it out.
If your exhaust is true duals, you may benefit from a cross over tube slightly smaller than the main exhaust pipes. This will give you some low-end back.
Quote:
Originally Posted by HUM GOOD
Custom mapping has been done already......i just feel the motor is taking in LOTS of air and not leaving fast enough.
I am also hoping to richin the sound up a little more. Don't get me wrong...the borla sound awful sweet....maybe one or two octives will satisfy me. ARE WE EVER SATISFIED? DO WE EVER GET ENOUGH?
Prolly not!!!!!!!
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12-16-2006, 11:31 PM
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Hummer Professional
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Join Date: Jul 2005
Location: New Jersey
Posts: 255
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Re: Exhaust?
Quote:
Originally Posted by tomp
Anytime you open up the exhuast flow, you drop back pressure which is going to reduce your low end performance. It's a trade-off
Most exaust companies focus on wide-open performance numbers and not on the low-end. I ended up trashing my first exhaust system to go with one that had better low-end performance.
Also, it may be a good idea to swap out the MAF sensor for one that can meter the air better. The OEM unit can only meter within a certain range of air and you may be outside of that range if you have not changed it out.
If your exhaust is true duals, you may benefit from a cross over tube slightly smaller than the main exhaust pipes. This will give you some low-end back.
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I dont have true duals, just catback borla. I want to go with the true duals but need to purchase another cat. So that whats leading me to look into my options. When the trues are put on I will also add the "H" pipe in also.
I haven't swapped out the MAF sensor. Who sells it and do you have a part #.
Thanks lots!
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12-19-2006, 11:05 PM
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Hummer Authority
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Join Date: Sep 2005
Location: Texas
Posts: 1,795
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Re: Exhaust?
Which air intake do you have?
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12-21-2006, 02:49 AM
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Hummer Professional
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Join Date: Jul 2005
Location: New Jersey
Posts: 255
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Re: Exhaust?
Quote:
Originally Posted by tomp
Which air intake do you have?
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The K&N
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12-21-2006, 04:22 AM
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Hummer Professional
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Join Date: Jul 2005
Location: New Jersey
Posts: 255
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Re: Exhaust?
Quote:
Originally Posted by tomp
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Thanks your the man......I'll try it out.
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12-21-2006, 05:48 AM
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Hummer Messiah
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Join Date: Apr 2003
Location: Virginia Beach
Posts: 37,474
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Re: Exhaust?
Quote:
Originally Posted by OrangeCrush
Is there really a big difference that would justify messin' with the cats? I honestly don't remember ever seeing any performance gains by removing normally operating cats.
Just wondering.... hate to see you spend a bunch of extra money for no benefit.
Mark
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I was told point-blank by three shops the "hi-flow" cats were no better than what we have already. I forgot the flow numbers and what the cell configuration is for the hi-perf cats, but it was all the same as our stock cats.
LPE didn't even offer them to us for our last truck with their engine in it.
__________________
"My reading of history convinces me that most bad government results from too much government."---Thomas Jefferson
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12-21-2006, 05:56 AM
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Hummer Messiah
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Join Date: Apr 2003
Location: Virginia Beach
Posts: 37,474
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Re: Exhaust?
Quote:
Originally Posted by tomp
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Good thought, but I've never heard of an independent dyno offering positive, increased HP, on those.
Quote:
Originally Posted by tomp
I think you'd be better off getting custom mapping done on your ECM. If you don't have it already, it's probably running too lean with what you have there.
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There's a homerun!!! Contact Dragon or TAZ through their website:
http://hummercustoms.com/default_hc.asp
They can hook you up with a Nelson program just for your truck.
__________________
"My reading of history convinces me that most bad government results from too much government."---Thomas Jefferson
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12-21-2006, 12:30 PM
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Hummer Veteran
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Join Date: Jul 2006
Location: Eastern PA
Posts: 149
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Re: Exhaust?
I've been very pleased with all ranges of performance and sound with the following mods:
Volant Cold Air Intake
Granatelli MAF Sensor
Bassani SS Catback dual exhaust (With exhaust tips tucked up
close to frame)
Superchip Programmer (In Tow Mode Setting Option)
Hope this helps!
__________________
2005 SUT: Firemist Red/Ebony; LUX; Sunroof; Uplevel Chrome Pkg; NAV; Air Suspension; Remote Start; Superchip; Volant CAI & MAF; 2006 Chrome SE Wheels & Front Brushguard; Front & Rear Cameras & Park Sensors With Audible Alarms & Digital Displays; Custom Tiger Stripe Interior Panels & Steering Wheel By OEMDASH; Bassani SS Exhaust; Wet Okole Seat Covers; Defenderworx Chrome Billet Tow Loops & Side Air Vents; HotShot System
1970 Pontiac Trans AM
2000 Mercedes SL500 AMG Sport
2006 C280 4Matic
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12-21-2006, 03:15 PM
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Hummer Professional
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Join Date: Jul 2005
Location: New Jersey
Posts: 255
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Re: Exhaust?
Quote:
Originally Posted by SUT NEIL
I've been very pleased with all ranges of performance and sound with the following mods:
Volant Cold Air Intake
Granatelli MAF Sensor
Bassani SS Catback dual exhaust (With exhaust tips tucked up
close to frame)
Superchip Programmer (In Tow Mode Setting Option)
Hope this helps!
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I'm pretty damn close to your set up.
K&N cold air intake
Borla catback dual exhaust with borla headers
Granatelli Diablo super tuner
and I just ordered the Granatelli MAF Sensor
Thanks for your input
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12-21-2006, 03:32 PM
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Hummer Authority
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Join Date: Sep 2005
Location: Texas
Posts: 1,795
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Re: Exhaust?
Also, I have never really looked into it, but that flattened exhaust pipe just below the tranny may be impeding exhaust flow. It is done this way to decrease the likelyhood of rattling from the movement of the engine/exhaust system. Any muffler shop would be able to tell you if it does. The canl fix it and install a welded on attachment with rubber grommet to reduce noise.
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01-03-2007, 12:50 AM
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Hummer Professional
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Join Date: Jul 2005
Location: New Jersey
Posts: 255
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Re: Exhaust?
Quote:
Originally Posted by tomp
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Change the MAF to the above. I was very surprised by the difference.
Better throttle response and I don't need to push so hard on the pedal to pass someone.
Thanks! For the positve help!
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01-03-2007, 05:44 AM
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Hummer Authority
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Join Date: Sep 2005
Location: Texas
Posts: 1,795
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Re: Exhaust?
np....
I liked the difference when I added mine too! I noticed the same benefits as you, plus a little more on the top end as well.
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