Over-Axle True Duals have RASP??
09-23-2014, 12:39 PM
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Staging Lane
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Over-Axle True Duals have RASP?? I just ran some true duals over the axle on my car. I used 2.5 mandrel bent piping along with two sweet thunder mufflers, an x pipe, and NO cats. The car is raspy if i get on it sounds like a old farm truck very flappy, yet sounds fine if I roll into the power really slow. What could cause this? When I had these mufflers dumps there was no rasp what so ever. I've watched other videos with people having almost this same exact setup with no rasp. I posted over on the true dual thread but was not getting any responses.
Last edited by SyntheticPro; 09-23-2014 at 12:44 PM.
09-23-2014, 01:21 PM
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Exhaust note can change with timing and mixture. If you
have two different WOT exhaust notes, it may be that
"where you leave from" fuel trim cell, one case or the other,
is pushing more enrichment as the LTFTs follow you to
PE mode if positive. And when my traction control pulls
timing around the corners, the exhaust note picks up a
pretty noticeable "honk" that goes away with the Low
Trac light.
Maybe there is some trimming behavior change that came
with the different plumbing (air reversion from the dumps,
sensor cooling from the headers, whatever - the sequence
of events, I don't know).
Question is, is it really sounding different under dead-same
conditions (TPS, RPM, gear) or just different because you
are driving it different? Some exhausts just don't do a good
job of quieting everything, everywhere and one made for
flow might be not so suave down low.
have two different WOT exhaust notes, it may be that
"where you leave from" fuel trim cell, one case or the other,
is pushing more enrichment as the LTFTs follow you to
PE mode if positive. And when my traction control pulls
timing around the corners, the exhaust note picks up a
pretty noticeable "honk" that goes away with the Low
Trac light.
Maybe there is some trimming behavior change that came
with the different plumbing (air reversion from the dumps,
sensor cooling from the headers, whatever - the sequence
of events, I don't know).
Question is, is it really sounding different under dead-same
conditions (TPS, RPM, gear) or just different because you
are driving it different? Some exhausts just don't do a good
job of quieting everything, everywhere and one made for
flow might be not so suave down low.
09-23-2014, 02:27 PM
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Staging Lane
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I'm not exactly sure about what you are talking about. But thanks for the response and I know for sure that at idle the tone didn't really change, but when you go WOT I get a lot of rasp/flap. I was thinking maybe it was the mufflers causing this.
09-23-2014, 11:30 PM
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Staging Lane
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here is a couple videos of the exhaust inside the car. After recording it and listening to it I can say it is no where near as bad as I was making it out to be; defiantly not as bad as a catback. But you can tell in the second video some of the "flap" sound I was talking about. 
