Yes, 2.5" tubes from the cats to the axle back. No other resonator just the resonated x-pipe. the resonated x-pipe will be mounted in the exact place of the actual y-pipe.
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Some questions about exhaust piping
- Thread starter baias6230
- Start date
The two huge departures from the stock system in your plan are effective diameter (stock is single 2.25" ) and resonator size/length. Both of those are going to change the sound significantly, with the resonator having a decidedly larger effect.
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Increasing the effective piping diameter by 247% (2.25" piping = 15.9^2". Dual 2.5" piping = 39.25^2" ) will have two effects. First, its going to slow down the exhaust gasses, which will allow them to cool more quickly, and *may* reduce the effect of exhaust scavenging (reduce low rpm torque). The reason I say "may" is that the change is also reducing restriction in the system, which is good. I don't know enough about the subject to predict the effects on performance, but suffice it to say it could go either way. At higher rpm scavenging becomes less of a concern while restrictions do the opposite, so there you will see gains. In regard to the sound - larger pipes make deeper exhaust notes and I'm not sure about how two smaller pipes changes that fact. My recent research has only been into single pipe systems.
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Resonators are a surprisingly complicated affair. In general they are tuned to specific frequencies, both in their size (length+diameter) and their location, so changes to either of those will have noticeable effects on the exhaust note. As an example; A 120Hz tone has a 1st order wavelength of about 9.5 feet. Therefore, if you experience a 120hz "hump" at a certain rpm range, in order to reduce that frequency at the tail pipe you would want to place a resonator about 9.5 feet from the source of the sound. This is how the location impacts sound tuning. The size in length of the resonator determines the frequency range that is effected, and the diameter of the resonator determines the reduction of amplitude (volume). Ie, a larger diameter resonator will reduce the volume more.
To summarize, you are reducing the length and size of the resonators, and moving them closer to the engine. The effects of these changes will be:
1) Reducing their size will make them less effective. This would matter if you were keeping the other variables (they would simply be less effective at the original frequency range), but since you aren't, its an apples/oranges comparison.
2) reducing their length will make their effective frequency range shorter. (instead of muffling 100-150hz tones they would muffle 120-130hz tones.) Again, if everything else were the same you may be able to predict the result...
3) Moving them closer to the engine raises the location of the effective frequency range on the audible scale. (Instead of muffling @ 120-130Hz, they would muffle @ 220-230Hz)
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Increasing the effective piping diameter by 247% (2.25" piping = 15.9^2". Dual 2.5" piping = 39.25^2" ) will have two effects. First, its going to slow down the exhaust gasses, which will allow them to cool more quickly, and *may* reduce the effect of exhaust scavenging (reduce low rpm torque). The reason I say "may" is that the change is also reducing restriction in the system, which is good. I don't know enough about the subject to predict the effects on performance, but suffice it to say it could go either way. At higher rpm scavenging becomes less of a concern while restrictions do the opposite, so there you will see gains. In regard to the sound - larger pipes make deeper exhaust notes and I'm not sure about how two smaller pipes changes that fact. My recent research has only been into single pipe systems.
.
Resonators are a surprisingly complicated affair. In general they are tuned to specific frequencies, both in their size (length+diameter) and their location, so changes to either of those will have noticeable effects on the exhaust note. As an example; A 120Hz tone has a 1st order wavelength of about 9.5 feet. Therefore, if you experience a 120hz "hump" at a certain rpm range, in order to reduce that frequency at the tail pipe you would want to place a resonator about 9.5 feet from the source of the sound. This is how the location impacts sound tuning. The size in length of the resonator determines the frequency range that is effected, and the diameter of the resonator determines the reduction of amplitude (volume). Ie, a larger diameter resonator will reduce the volume more.
To summarize, you are reducing the length and size of the resonators, and moving them closer to the engine. The effects of these changes will be:
1) Reducing their size will make them less effective. This would matter if you were keeping the other variables (they would simply be less effective at the original frequency range), but since you aren't, its an apples/oranges comparison.
2) reducing their length will make their effective frequency range shorter. (instead of muffling 100-150hz tones they would muffle 120-130hz tones.) Again, if everything else were the same you may be able to predict the result...
3) Moving them closer to the engine raises the location of the effective frequency range on the audible scale. (Instead of muffling @ 120-130Hz, they would muffle @ 220-230Hz)
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In regard to retaining the "VQ sound", I don't think you'll be able to do that with your plan. An example of a system that does is the NISMO s-tune system, which incorporates a single resonator in the stock location that is only slightly larger in diameter (to compensate for the increased volume of the larger piping diameter.
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I suggest finding a system that you like (sound) and mimicking it with custom parts. If you want to stay close to the oem exhaust note, keep your changes as small as possible. Trial and error gets expensive quick...
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I suggest finding a system that you like (sound) and mimicking it with custom parts. If you want to stay close to the oem exhaust note, keep your changes as small as possible. Trial and error gets expensive quick...
