Alpha Exhaust... BIG DISAPPOINTMENT!

I bought a s.s. magnaflow muffler for an 02 trans am and some square tips  also from magnaflow. I had a fab. shop bend me some duals for my alpha and it looks tits... but dispite the straight-thru design YOU COULDN'T HEAR ANYTHING! So we took off the resinator... a little better, nice quiet rumble but nothing close to what I expected. After further exploring on the lift whats this? 4 friggin cats on the alpha. Sorry guys. the only way to get a decent sound outta our 5.3's is removal of those damn "pre-cats" and then maybe we'll have some o2 problems. Maybe we can use o2 simulaters?

Alpha Offroad,
How ironic you tried this. Just last week when I had my H3 Alpha in the shop to adjust the torsion bars and replace the front shocks we lifted the truck to "look" underneth and discussed doing the same thing. I was shocked to see the 4 cats and then the muffler sideways for even more restriction.
Is that a cat in the very middle of the truck or the resinator? I wanted to remove that and put a high-flow muffler in it's place and then have dual pipes come out of that and exit out the rear. Is that what you did? I don't want to start down that road with o2 problems, otherwise I'll just leave it as it is. In NY the vehicle won't pass inspection without the cats in place as they do a o2 test. They plug the vehicle into a computer and can tell immediatly if someone has been tampering with the cats or o2 sensor.

check after each "cat" to see if there is a sensor...if not then that cat (more likely just a resonator) can be removed or gutted without fear of throwing an CEL (check engine light) If there is a sensor you can still replace that cat with a higher flow one that will flow more and improve sound. Cats operate on heat, there will not be a cat towards teh back of the truck..just not enough exhaust temp that far back, anything back there is a resinator...take em off!!! 

IK,
  I had talked to an muffler shop about removing the resignator, they said that the biggest difference it would make would be increased drone on the highway and would sound about the same at idle.  Do you have experiance with removing the resignator on the I5?

not on the I5 but all a rsinator is is basically a single chamber straight through muffler...removing it will increase sound. I know on my wifes old Beretta I couldn't get good sound no matter what I did....I removed the resinator and the sound was great. The less meffled any exhaust is the more sound...so removing a resonator can only make things louder...then the mufflers job is to make the note deeper.

There both cats. Pre-cats just off the manifolds then cats then the resinator then the muffler. Pretty restrictive. 

Why dont you Alpha guys just get the Flowmaster made for the Alpha, sounds like it would save a lot of hassle?

quote:

ORIGINAL: Alpha Offroad

There both cats. Pre-cats just off the manifolds then cats then the resinator then the muffler. Pretty restrictive. 

 
yea, so like I said...remove the resinator and sound will increase, or go with high flow cats.

I agree with IK, and you would be suprised what a set of hi flow SS cats (the back set) can do.  The front ones require more work because of sensor issues.

I have yet to see one offered for the Alpha???

quote:

ORIGINAL: mfish

Why dont you Alpha guys just get the Flowmaster made for the Alpha, sounds like it would save a lot of hassle?

quote:

ORIGINAL: ALPHA XY

I have yet to see one offered for the Alpha???

quote:

ORIGINAL: mfish

Why dont you Alpha guys just get the Flowmaster made for the Alpha, sounds like it would save a lot of hassle?

 
 because neither Magnaflow or Borla have made an exhaust available to the public YET! But they say it's coming soon.

I think Mfish meant to just get a flowmaster muffler and have it made to fit the alpha? Any muffler shop can take a universal muffler and weld it into the alpha.

I think there are too many restrictions in the stock exhaust system. Replacing just the muffler or actually even installing one of the so called hi-flow systems does not replace the 90 degree bends at the muffler. I would prefer to move the muffler midships and run dual tailpipes straight out the back.

I agree...I hate the stock muffler position on all the h3's. I assume the alpha is similiar. I would just go to a muffler shop (if your not a good welder) and have them remove everything from the cat back, weld on a flowmaster 40 series muffler with single in dual out and run dual 1/2" pipes out to the rear bumper. You'll have enough backpressure from the cats that going dual 2 1/2" pipes won't kill your low end torque. It should cost you around $400 to have all this done. And you'll get nice sound from it. Or if you want to go extreme, you can always go header back with a crossover pipe to equalize the exhaust pulses and smooth the tone out, then you'll have a real nice powerful sound. BUt that'll run you a grand or so at a good shop.

I had a guy that muffler shop here told me that he could do the dual Flowmaster 40 for about $430. I'm assuming that is what you're talking about. I wish I had about 2 grand laying around. Exhaust, hilljobs roof rack, PCMforless, Granetelli MAF.  Oh yea, the atlas transfer case too. Guess I should wish for about 4 grand

$430 sounds fair, I have had exhaust done by the same guy for my last 12 cars/trucks so he cuts me a break....I could have the h3 done for $300 through him. I just didn't like the sound of a flowmaster 40 on the I5 so I never had it done. 
 
I've had the atlas II sitting in my shop for a year or so now, got it from a junked truck for $350. The junkyard guy had no idea what it was, guess I got lucky. Now I just need a truck to put it in. I'm hoping that sometime in the future I'll have enough money saved up to buy an old 1970's Chevy 1/2 ton pickup with a 454 and rebuilt it, then I'll use the atlas in that....the way things are going I don't see that kind of extra cash for a long long time

quote:

ORIGINAL: importkiller
I agree...I hate the stock muffler position on all the h3's. I assume the alpha is similiar.

 
My bro-in-law has a 07' I5 so I will look to see if the muffler position is the same as my 08' Alpha.
 
The Alpha has 4 cats and I'm wondering if removing the one midships and replacing it with a hi-flow muffler would screw up the computer. If not, then I'd like to do just that, a single hi-flow muffler with dual tailpipes straight out the back, all stainless of course.
 
But then I'd still need a hi-flow intake or air filter to compliment the exhaust. Nothing available yet!
AIR IN, AIR OUT

even if it does have 4 cats...which I don't believe it does, but haven't seen it so I'm not sure. But even if it does have 4 cats the rear ones are more than likely not monitored...just won't build up enough heat for an 02 sensor to function properly back there.
 
I don't understand the 4 muffler thing...I assume there is one in each manifold, does the manifold go into a collector then there is one pipe going back? Or is it true duals going back? I think there is only single pipe back so where are the other two cats? Two in manifolds, one after collector about mid frame then one near the rear axle? IF that is the setup you have then the one by the rear axle is not a cat...it's a resinator...completely different part and not monitored by the PCM.

I don't know about the I5's and it's too damned cold and windy out there right now to go look. But looking at the Gibson diagram for thier exhaust it only shows the muffler and pipes from the front CAT back. Seeing as how alot of guys on here have it, I'm asuming it doesn't cause a problem. None of them have said anything about it.

the I5 has a manifold cat, an front inline cat and a rear resinator....the gibson exhaust removes the resinator and puts a muffler in it's place, then runs dual pipes to the rear bumper. This is the ideal setup IMO...the resinator does nothing but quiet the exhaust and is not monitored. A lot og guys confuse the two but the resinator is completely different.

quote:

ORIGINAL: importkiller

even if it does have 4 cats...which I don't believe it does, but haven't seen it so I'm not sure. But even if it does have 4 cats the rear ones are more than likely not monitored...just won't build up enough heat for an 02 sensor to function properly back there.

I don't understand the 4 muffler thing...I assume there is one in each manifold, does the manifold go into a collector then there is one pipe going back? Or is it true duals going back? I think there is only single pipe back so where are the other two cats? Two in manifolds, one after collector about mid frame then one near the rear axle? IF that is the setup you have then the one by the rear axle is not a cat...it's a resinator...completely different part and not monitored by the PCM.

 
 
importkiller,
I really don't know much about it and I'm going on what my guy at the shop told me. Check this out here: http://www.hummerforums.com/m_130027/tm.htm Are you saying that the muffler looking thing midframe is actually a resinator? Could the Alpha actually have two cats and two resinators? I'm going to a New Hummer Owners Seminar on the 27th and maybe I can ask someone about that.
 
rhill20,
Samesame here! It's nasty out otherwise I'd go take some photos of the exhaust system and post them but I don't feel like laying in the snow.

unless there is a picture of the system it's hard to say. I just don't see how a  cat would work that far back...cats work on heat...they need heat to get the "waffle" inside to do their job of filtering out the nitrogen. On a cold car the cat does absolutely nothing until it heats up, this is why most are placed as close to the motor as possible without getting it so hot that the element gets burnt up. Automakers have played with the idea of using an electric heating element to have the cat already warmed when you first start your car but nothing has come of that....so that being said I don't see why GM or any brand would put a cat that far back in the system cause it wouldn't work. There was actually a company making a high performance exhaust for the new lancer and they swore there was a cat right by the rear axle till I took mine off and cut it in half...it was just a resonator, just like I assume is on the alpha. ...My guess without seeing it is that there are two cats in the manifold...not really traditional cats, new technology, then there is a mid stream cat with a up flow sensor then a resonator then the muffler

Would there be a reason NOT to go with the Dual Extreme? The one where the tailpips come out on the sides (one on each side). Was thinking (I have one of those trailer hitch baskets) that it would be better so as not to melt my cover on the basket carrier.

I really have to take the camera out and get under the Alpha...but it is waaaay to windy for that today!!

I think I am just going to build my own system. Catback, flowmaster 40 or 44 placing it where the res is now and running strait out the pass side (like the H2 aftermarkets).

quote:

ORIGINAL: rhill20

Would there be a reason NOT to go with the Dual Extreme? The one where the tailpips come out on the sides (one on each side). Was thinking (I have one of those trailer hitch baskets) that it would be better so as not to melt my cover on the basket carrier.

 
kinda like what I had on my Dodge
 

 
I like that setup...looks cool IMO