Exhaust?

[HUM GOOD]

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.

[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

[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.

[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.

http://www.scarichi.com/sito_ita/images/cat_3_2.jpg
http://www.scarichi.com/sito_ita/images/cat_3_1.jpg

[HUM GOOD]

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.

http://www.scarichi.com/sito_ita/images/cat_3_2.jpg
http://www.scarichi.com/sito_ita/images/cat_3_1.jpg

Ernie, very interested in this Turmax....is it available in th US. All my searches come up in Italian.

Do these effect the sound?

[HUM GOOD]

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.

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!!!!!!! :jump:

[Ernie Italy]

Ernie, very interested in this Turmax....is it available in th US. All my searches come up in Italian.

Do these effect the sound?

A little bit...the sound is more breathe and "open". Not loud... I like it

[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:crying:

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.


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!!!!!!! :jump:

[HUM GOOD]

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:crying:

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.

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!

[tomp]

Which air intake do you have?

[HUM GOOD]

Which air intake do you have?

The K&N

[tomp]

I'd say that the MAF is restricting you more than the CAT is. Go with the Granatelli MAF: 350120-C

http://www.granatellimotorsports.com/gmmaftruck.htm

[HUM GOOD]

I'd say that the MAF is restricting you more than the CAT is. Go with the Granatelli MAF: 350120-C

http://www.granatellimotorsports.com/gmmaftruck.htm

Thanks your the man......I'll try it out.:dancingbanana:

[KenP]

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.

MarkI 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.

[KenP]

I'd say that the MAF is restricting you more than the CAT is. Go with the Granatelli MAF: 350120-C

http://www.granatellimotorsports.com/gmmaftruck.htmGood thought, but I've never heard of an independent dyno offering positive, increased HP, on those.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.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.

[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!

[HUM GOOD]

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!

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

[tomp]

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.

[HUM GOOD]

I'd say that the MAF is restricting you more than the CAT is. Go with the Granatelli MAF: 350120-C

http://www.granatellimotorsports.com/gmmaftruck.htm


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!

[tomp]

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.

[HUMMERcustoms.com/TAZ]

The MAF was a good option to add as long as you are using handheld tuners with the shorty headers as all they do at the non-forced induction is get the throttle response. They really should not be so radical as to help low end but, can on short's yet will not help long headers as they take care of that for you. So there is a plan to it all to cut cost by planning it out up front and get the most bang for the buck. In my research with many guys they stick with stock because of the cost of MAF and use money in another area like laptop tuning software to tweak like a handheld cannot get close to and cause you to go to colder plugs to hold off detonation with farther timing adjstments that handhelds can do. A handheld we used did a great job before SC but, when i had a talk with a friend that did laptop tuning for people He said as a rule he get can gain without danger 75HP and even more torque over handhelds. But, keep in mind handhelds have liability issues where if you go to a tuner You are asking to do something with risk involved but, you choose how much. I may blow my motor but, I have sponsor backup if i do for another. If You really want to go wild go with HPTUNERS tuning software and because even the aftermarket MAF help only so much. With HP tuning You can get like 2 bar density if You go forced induction and remove MAF completely and give the PCM the air flow numbers You want it to think it is reading. It is all based though on wideband sensing and other parameters.

They have even a basic and a 1, 1.5 and up for none forced induction to solve the poor air flow reading that comes with even performance MAF. If you are running cold air intake and buy the MAF did You make sure to ask for the cold air calibrated model because if not You are no better off than with stock. Reason is You increased air flow through MAF and they make for same rig a upgraded model for factory air intake and aftermarket cold air intake. They bench calibrate them specially for the performance air intake. The other perf. MAF may or most likely will not help over the stock and You wasted $275 to $360. But, this is stuff the seller should ask you but, most forget so the only dumb question is the one not asked. But, i have dealt with peformance stuff all my life so i develope a laundry list of stuff i want and in what order to get to maximize the project.

But, if You have spent the money on tuner and MAF upgrade You have done about as good as You could get as long as You got the correct stuff for situation You are in, which is not bad. Before i went supercharger i ran handheld with electric fans everything i could add with Dynatech long tube headers with catback system and the little You loose by opening up the exhaust flow You get back with long neck or tube headers.
I have from more experienced performance people than me tell me the catback system matched to the header flow helps over stock, so i went that way. You would need to read allot of research and numbers to really get to the bottom of it. Like a flow meter or maybe a wind meter behind a stock cat versus perf. cat. My Hummer dealer who has a very perf. oriented service manager told me not to mess with perf. MAF and to use the Perf. cats.
I also have a connection with a friend that has made several new items introduced at SEMA and won awards for some and he is a perf. guru to allot of the state and he says not to go after market MAF and yes to cats as well. So I picked allot of brains to increase my knowledge to help myself and others when they asked what i think. So that and $3 will get a cup of coffee.
With the short tube header if you go to true dual exhaust I would recommend a little more restrictive muffler by meaning maybe a little quieter flowmaster 40 or 50. I run super 40's which flow real fast and are real deep sound. But, I need all the flow i can get because i'm using forced induction so back flow is a killer. I will at some point put LS6 heads and cam in The Beastly Beauty and go to high compression using a piston introduced by the buddy in SEMA 2006 although i saw it in 2005 allot and saw his genius on this piston. It makes You think why did someone not think of this till this late in time as far as peformance goes for last 100 years.

Each rig has to be thought about what You think You want to do with it from the day you buy it and research ask questions and before You buy your first exhaust improvement or any performance stuff take the time to talk to many people and see what is working. Go to all the performance forums you can find that may cover your rig and if not they may talk about the motor you are runnin as in H2 many rucks run that motor and in truck forums they talk about this stuff as well.

I will never after experience have anything but, Dynatech catback system. One reason it is all stainless so no rusting out. With them and stock MAF along with handheld tuner and allot of messing with settings using a G-tech Pro we got 400HP at the wheels no forced induction and my rig ran like a scauled dog using low octane to get hotter burn with handheld. I had even thought about going to hotter plugs. Low octane fuel has more power than higher octane because it has a lower flash point so more power eeleased more quickly. When you go to forced induction You then begin the dance of how low can i keep octane for power yet control it wih sprays to keep fuel and air cooler as well as all you can do to keep engine temp down. You gain power from timing more than fuel so the concpet chnages as to what you are trying to accomplish. Tweaking becomes of great importance and being patient. If not it blows up quick. But, i selected each part to go with what i was adding to make it all work good together keeping in mind that even though i was not running forced induction and knowing i wanted to go to tuning myself with laptop I tried to pick in advance that would work best up front and do the same moving on towards later goals.

You will hear many suggestions but, You just got to take it all and sort it out if You do not have someone with the experience to ask first how would You set this up. I have the way i would recommend because i did consult the top performance people in our area and they had been putting add on power for years on different rigs including already experimenting with H2's back with 2003 models bu, mostly just rigs of different kinds with 6.0L. I tell everyone to please find a performance exhaust shop not just local muffler shop. I have a friend who owns a great muffler shop and does quailty work but, i would not take his advice on performance nor will he give it as he fixs dailly drivers all day everyday. The guys that are serious about perf. and sound seek out the perf. exhaust shops.

Well the thing is I have offered allot of info and there are others that may disagree. But, Dragon and I have put about 550HP on the ground right now and that is at roughly 8lbs. of boost and we are going to continue to raise boost with additional mods and get to 750hp next which we will do i think just by adding the water/meth inj. and going to real tight tweaking on the HPTUNERS software. We will go to 2 bar density so we can take MAF out of system and run boost up a little with each tweak to the point We need to shoot co2 spray on supercharger aftercooler to get more of temps done and move to 120 octane on our way to as close to 1000HP as we can get. Not to run it all the time at it but, to get it there and then do some mile trap runs to see how fast a box with wheels can go then take it back done to fun power around 700Hp and just play with tuning all the time.

Allot of what we are doing would work for others here but, if You off-road i do not recommend you go to forced induction as it just adds more stress to an already extremely stressed rig with just the light performance addons.

I'm happy to talk with anyone before they start if You PM me to start the dialoge of where you are and where You want to go. You do not have to buy a thing from us. What Dragon or I share here is to be of help. But, We are doing allot of radical power things as time goes by and Dragon has got to finish the new electronics upgrades soon so can get to more advanced tuning for summer run in mile speed trap. I'm anxious to get the 2bar tuning and get rid of MAF and freak people out at shows.

Glad to help if i can.

TAZ

[HUM GOOD]

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.

I also have recently notice the top end just feels looser. Not as much back down when releasing the gas.

I am very satisfied.

[HUM GOOD]

TAZ

Awesome write up. I appreciate the time in explaining and giving guidance in this area.
Most of that is above my head. i will not be running forced induction.
I do run a hand held and short headers and now replace the MAF with a performance. Although the tune has not been played with much. Now that I have all mods installed, I will be placing the truck on a dyno and fine tuning it for the best tune for my everyday runner.

Thanks again!

This is a great site!

[HUMMERcustoms.com/TAZ]

You are Welcome Hum Good. I try to help I just have a hard time in condensing what i want to say. But, that is a joke from all the old hats that we have been running for a few years about me. A few suggested that each of my posts should be counted 10 for each one. Sometime it is hard to get all options to be taken in a short note. I do not achieve it often enough but, I like to eb as detailed as i can.

TAZ