RE: Alpha Exhaust... BIG DISAPPOINTMENT!
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RE: Alpha Exhaust... BIG DISAPPOINTMENT! - 2/10/2008 5:51:06 PM
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ALPHA XY
Posts: 123
Joined: 12/9/2007
From: Rockville, MD
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the flattening out of the driver side pipe to cross under the x-member is what I was  at when I was under there today?? Don't you think that interrupts flow making for an unblanced exhaust pluse?
All the cats and res's/goofy bends, Nissan Z esque muffler......we have to figure out something better guys! :)
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RE: Alpha Exhaust... BIG DISAPPOINTMENT! - 2/10/2008 11:16:42 PM
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TheGunnyRet
Posts: 307
Joined: 11/21/2007
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Man, what a mess. Everything after those cats is just sound reducing resonators or whatever you want to call them.
Here is what I think, I would see if the MAC GM 5.3 Headers fit, look at Dr Gas for an X-pipe that has a 90 degree bend off one leg then run that to a Spintech dual in and out and split them out the back.
The other thing you could do is volunteer your Alpha to one of the major Exhaust Makers if you live close to them.
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H3Black2007.5
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RE: Alpha Exhaust... BIG DISAPPOINTMENT! - 2/11/2008 4:07:41 PM
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alphadogg
Posts: 358
Joined: 12/30/2007
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I agree with TheGunny, what a mess! When I have the extra coin I'm going to replace the mid-truck resonator and install a hi-flow muffler in it's place, then some how with dual tailpipes exit out the back. There's a muffler shop in my hood that does custom work (bending etc.) and might be up to the task. I'll go by and see what the muffler shop says and let everyone know what the verdict is.
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RE: Alpha Exhaust... BIG DISAPPOINTMENT! - 2/12/2008 8:08:51 PM
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Alpha Offroad
Posts: 12
Joined: 1/26/2008
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Regardless the alpha has 4 cats. How many time does a man have to say it. I talked to a g.m. tech and he told me their monitored before the first cat and after the second cat. And removing or altering any of them could cause you to throw a o2 code. My only option with removing the pre-cats it to park my alpha,core my ecu.and get a new comp. tune to accept the loss of backpressure and possibly advance spark,time.,air,fuel, but you hafta run 91oct. Or get o2 simulators--- they make them for late model muscle cars.
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RE: Alpha Exhaust... BIG DISAPPOINTMENT! - 2/12/2008 8:15:05 PM
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Alpha Offroad
Posts: 12
Joined: 1/26/2008
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Alpha dog if It wasn't a blizzard here in the D I'd record a m-peg of my Alpha with dual s.s. magnaflo(straight -thru) exhaust and no resinator. It has a slight gurgle and growl. Much improved from stock but far from what it should be. I'll get it posted a.s.a.p
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RE: Alpha Exhaust... BIG DISAPPOINTMENT! - 2/12/2008 9:40:00 PM
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TheGunnyRet
Posts: 307
Joined: 11/21/2007
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I don't know? Looking at those pics I think you only have 2 cats, normally they do not put an O2 sensor after a muffler/resonator. As IK stated you need heat on the cats and that Giant Resonator Can is to far from the heat and no O2 sensor by it. The GM Dealer Techs are not necessarily always right. If you are so worried about back pressure why are you wanting to change your exhaust? Replacing the muffler will affect your back pressure.
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RE: Alpha Exhaust... BIG DISAPPOINTMENT! - 2/13/2008 7:57:55 AM
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Steve #1
Posts: 412
Joined: 7/29/2007
From: TEXAS
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Ok, why is having 4 cats a bad thing?
It's my understanding that by separating the converter in to multiple stages, it increases its effectiveness which allows it to be designed with less restriction.
If I'm wrong, please explain.
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RE: Alpha Exhaust... BIG DISAPPOINTMENT! - 2/13/2008 3:43:46 PM
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alphadogg
Posts: 358
Joined: 12/30/2007
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Today I went to a local muffler shop that specializes in custom bending for custom exhaust systems. He lifted my H3 Alpha and this is what we saw. There are 4 cats, two on each side before the collector, I don’t know if they are both monitored but the technician said they must stay (NYS law). After the collector was the resonator (mid truck), he said we could replace that with a new muffler with dual tailpipes exiting out the back of the truck.
Of course it would take some custom bending to maneuver around things underneath to exit at those indentations at the rear bumper with my choice of polished stainless tips. He had three different stainless mufflers to choose from, quiet, semi-loud and loud, the system included all stainless pipes, stainless welding rod, stainless hangers all installed for and guaranteed $660+tax. He could have done the job right on the spot but I didn’t have 3 hours to kill so if I want the job done I’ll have to go back. He also said he’s already done several Alphas and they have turned out great!
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RE: Alpha Exhaust... BIG DISAPPOINTMENT! - 2/13/2008 7:12:44 PM
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Doc Olds
Posts: 3805
Joined: 7/11/2007
From: Boat Town USA (Michigan 48045)
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Patches Quote: "The driver's side "pre-cat" or "pup-cats" as they are also known. There is one of these coming off each of the exhaust manifolds, driver and passenger, just after the O2 sensor. The pup-cats light off faster than the main cats to keep cold start emissions low."
Thanks for the pics Patches!!!! a big help. My concern was I assumed (wrong) that the manifold CATs would be monitored, but as we have discerned, none are??? Like IK posted in CAPS   back at post 54. So, if your state laws allow removal or replacement of at least the pipe cats (the second set) to high flows, it may?? be of some benefit sound and performance wise.
Gunny, I agree...........what a friggin mess! IK, the flat spot in the I5 exhaust, ain't that flat.
If it were me, I would wait for an aftermarket CAT back kit, they are almost set to be released, (see MAGNAFLOW H3 Alpha Exhaust - Very Close to AVAILABLE!!!! ) and if after installing one I needed more sound, I would add high flow CATs to replace the second set.
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RE: Alpha Exhaust... BIG DISAPPOINTMENT! - 2/13/2008 10:17:22 PM
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TheGunnyRet
Posts: 307
Joined: 11/21/2007
Status: offline
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I guess you can't leave well enough alone, to throw a wrench in this I would see if the MAC 5.3 headers fit, wait for the Magnaflow. I know for those who start changing stuff to soon then all of a sudden the aftermarket catches up, BAM! "I just wasted my money because of my impaitients." Plus I am glad I live in SC no sniff, no nothing and only 1 licsense plate.
By the way REAL nice Vette exhaust in that link.
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