Yet another exhaust thread....

2557 Views 12 Replies 8 Participants Last post by MaranelloRacingCars, May 3, 2007

cardiffGiant

Discussion Starter · Apr 16, 2007

I am heading to the exhaust shop for some further modifications to my system. I have the back boxes off now, and find it a little too loud at idle. So I am considering a process like this, if anyone thinks there is a better way of going about this, please do let me know as I am no expert:

1. Baseline Dyno
2. Remove center resonator
3. 2nd Dyno run
4. If the second run is higher, keep center resonator off and add round body magnaflows in place of the resonator. (I'm sure pure straight pipes will be much too loud, and am hoping the magnaflows will make things slightly quieter than the stock resonator.) If this isn't the case, I suppose I will need to chop into the straight pipes where the back boxes were, as this is the only place with room to add something else.
5. If the second dyno run is lower than the base line, then I will try to add smaller magnaflows just after the resonator where the double bends in the pipes are now.

My thinking on this sequence is that from some reading, it seems that the center resonator on cars is designed with sufficient volume to make the cat back portion of the exhaust to appear to be an open system to the engine, so I am unclear whether removing it may have adverse effects rather than positive ones on exhaust performance.

Question is, does the computer adjust instantly to the different flow characteristics of removing the resonator, etc. (Will the second dyno run show a valid difference in its results, or does it take the computer time to recalibrate?)

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BeeYouZeeZee

· #2 · Apr 16, 2007

cardiffGiant said:
I am heading to the exhaust shop for some further modifications to my system. I have the back boxes off now, and find it a little too loud at idle. So I am considering a process like this, if anyone thinks there is a better way of going about this, please do let me know as I am no expert:

1. Baseline Dyno
2. Remove center resonator
3. 2nd Dyno run
4. If the second run is higher, keep center resonator off and add round body magnaflows in place of the resonator. (I'm sure pure straight pipes will be much too loud, and am hoping the magnaflows will make things slightly quieter than the stock resonator.) If this isn't the case, I suppose I will need to chop into the straight pipes where the back boxes were, as this is the only place with room to add something else.
5. If the second dyno run is lower than the base line, then I will try to add smaller magnaflows just after the resonator where the double bends in the pipes are now.

My thinking on this sequence is that from some reading, it seems that the center resonator on cars is designed with sufficient volume to make the cat back portion of the exhaust to appear to be an open system to the engine, so I am unclear whether removing it may have adverse effects rather than positive ones on exhaust performance.

Question is, does the computer adjust instantly to the different flow characteristics of removing the resonator, etc. (Will the second dyno run show a valid difference in its results, or does it take the computer time to recalibrate?)

The only mod I have done is to remove the "central silencer" as Maserati calls it. The hope was to add a little more volume to the exhaust note. It may have but I'm unclear on whether it made a power difference. Looking inside the Central Silencer it's clear it's a straight-through resonator going through a perferated tube. No direct baffeling (looks like a glass pack). I left the X-Pipe and rear boxes in place. I may put the Central Silencer back in since I didn't notice much of a change and go with rear muffler replacements.

The computer automatically adjusts for changes and doesen't throw a CEL.

Buzz

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