hello everyone , i have a problem i hope someone out there can help me with it, i'm thinking of slowly changing my exhaust i was thinking of cuting out the resonator and adding a blue bottle or just running strait pipe to the mufflers out back what power gains if any are there will this help the flow ???? and will it make the exhaust a bit louder??? i have looked on u-tube and have seen several post but knowone has said what it has done for fuel economy..also what would a high flow magnaflow cat do for me... i'am in the procces of changing o2 sensors up and down stream are these easy to remove as i have not tackled this ever.. i usually leave this up to the guys at the muffler shop to do any help and info on these matters would be greatly appreciated....

 

Replacing or removing the resonator will make it slightly louder. Some that have replaced it with straight pipe complain about drone (low frequency vibration). I replaced mine with a Magnaflow 30" glasspack and have no drone. The biggest restriction in the exhaust is the 'U' bend where the downstream O2 sensor is located. Since you're contemplating replacing the cat you may want to look into a down pipe, That way you can eliminate the 'U' bend the same time you replace the cat. Removal of the O2 sensor isn't too difficult, but they can be stubborn. I would spray it with PB Blaster the night before, and again a couple hours prior to removal. You'll need an O2 sensor socket (you can get a loaner at the part store), a breaker bar and extension. I suggest replacing it with either an AC Delco or Delphi brand sensor. Many have reported problems with other brands. Whether or not you will see an improvement in mpg is hard to say. I saw an increase of 3.7 mpg after replacing my downpipe/resonator and installing a CAI, but my cat was beginning to clog.

 

thank you so much for the reply, its good info i have looked into getting the cat replaced at my local muffler shop they want to sell me the same magnaflow direct fit cat system that i can buy off ebay for cheaper then what they will charge me lol lol..i may look into getting that u-bend removed i have looked on u-tube and have watched a video on this looks like tons of fun to play with lol......

 

I replaced my stock down pipe with a better flowing ZZP downpipe (which has a high flow cat and u-bend delete). This may have yielded a little MPG improvement. I was looking for better performance, and this is a wise supporting mod for other mods I was planning.

I later got rid of my resonator and have a straight piece of pipe. Just doing that, the Butt-Dyno noticed a small HP improvement.

Honestly, I would not worry about the downstream O2 on these cars unless you are getting a check engine light (to the best of my knowledge on the '00-'05 Montes, the downstream O2 does not affect MPG, but the upstream can). Also, because of the U-bend, the downstream O2 is a PAIN the work on if it doesn't easily break free (the tunnel where you have to work has limited space for ratchet movement and cheater tools). I highly support )3SSLE in the recommendation of a Delco or Delphi O2. With emissions regulations getting tighter, the PCM programming is getting more sensitive to a set of precise readings, and some other O2s are borderline how precise they are.

As for the U-bend being a big issue. I've debated that. To the best of my knowledge, it flows the same volume of exhaust gases as a straight piece of pipe. But, if you're going to get a ZZP pipe because of it's wider inside diameter and the high flow cat, it deletes the u-bend anyways, so it's not even worth debating IMO at that point.

Last point, a high flow cat is a cat that is to allow more exhaust gases to pass through the system, letting the car "breath" a little better. One problem using this OR a non-oem cat is that you may throw a P0420 code (just like the O2, the PCM is tightly calibrated to specs of a specific CAT). The problem with this is you can have a non-OEM cat, everything works just fine and still have a P0420 code, which then causes problems passing some emissions checks. Now, I have a ZZP DP with high flow cat. It never threw a code in the year I had it before having my PCM re-tuned and during that time the code deleted for good. I've passed my local emissions check both by their computer scan AND doing a tail pipe exhaust check. Results were always fine. If you are concerned with the P0420 code, check the link below, I offer a code delete service:
https://montecarloforum.com/forum/pr...impalas-42773/

I hope this helped answer some questions. One last thing. I also have the ZZP front header known as a PLOG (Power Log) and the rest of my exhaust that I have not mentioned, including mufflers, is stock. I don't notice the sound drony or any issues with it. I'm happy with how it all sounds. Just my opinion.

 

thanks again for the replys, i have got the upgraded o2 sensors my friend ckecked the code for me on his scanner it is the down flow 02 sensor thats causeing me the problem... theres lots of things to consider when i do this not to many people carry theses pipes in stock they all want too order them in, canada is different from the states for getting the parts quick and costs alot less one shop wants 230.00 and probly shipping on top for the pipe alone and 80.00 to 110.00 for shop time to install...

 

im also using bosch premium o2 sensors

 

No, no, NO!!! Bosch O2 sensors are the ones most known in the 3800 crowd to give you problems!
Admittedly, I have a BOSCH on my wife's 3400 Impala, but ONLY on the downstream (it's less critical there).

But I highly recommend NOT using a BOSCH in the upstream! I don't know from first hand experience, but there are too many threads on 3800 forums about people who have had problems, if it were me, I would not even try it.

STICK WITH AC DELCO OR DELPHI O2 SENSORS!

I tried a Denso on my Monte's upstream and had problems. Once I popped in a Delphi, it went away.

What code are you getting on your downstream O2? If it's P0420, it *might* be the cat beginning to fail and not the O2.

Also, NEVER use BOSCH spark plugs in a GM V6 engine. I have had first had experience, they SUCK! AC Delco or NGK plugs, that's the way to go. BOSCH plug wires are fine, just not plugs or O2 sensors.

 

haha this was basically what i was researching as well, hey maniac i forgot to ask, when you got the wider zzp downpipe was it a pain to install seeing though it is wider or was it shop installed? when i order mines i was just gonna have a muffler shop install it

 

I installed my ZZP DP. It was a piece of cake (and I was lucky no bolts or studs snapped). The mating surfaces of the flanges mate up just fine. The wider part is the inside diameter of the pip (keeping it true to what the mattering surfaces allow). The stock pipe on the inside tappers down (bottle necks) and you lose flow....

 

Thanks for the info on them but i have already installed the damn things what a pain but its done it did put the engine light on but im at a friends place and i dont have my scanner here to check it. ....im hoping its not the cat but if it is iii change it out too the down pipe and u bend delete thanks for all the help this form is great ......