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Old 12-08-2017, 09:06 PM   #7
911monty
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Join Date: Oct 2014
Location: California Central Coast
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Just my .02. IMHO I think it is counterproductive to purchase a free flowing exhaust only to restrict it with baffles. I'm by no means an expert but I did some research on the issue while trying to quiet high compression big block engines. The drone these things made was crisp, high pitch and ear bleed loud at cruising speed, at 6500 rpm? Glorious. Even 70 series Flowmasters designed to quiet motorhomes wouldn't help.
What I found is that drone is caused by the uneven firing order between banks causing unequal pressure pulses in a true dual exhaust that creates a harmonic distortion kinda like "clipping speakers" to your ears. To address this there are balance tubes and the Gas X crossovers that even out those pressure pulses between banks. This is not possible in these cars and is why the stock muffler has the balance tube inside it. But yes it's heavy. We really need someone to think outside the box and come up with some sort of crossover for these cars, but the additional pipe may negate the weight savings. Otherwise it's modifying the stock muffler although I think as bypasses get larger then drone will also start to increase. Porsche created the PSE so it can be loud when mashing the pedal and quiet when cruising, but it's even heavier with the additional piping and valves. Good Luck.

Oh Yeah in case you were wondering what happened to the noise of the big blocks? With the simple addition of the balance tube the sound went from the ear bleed loud to a nice mellow rumble. It was truly remarkable.

Last edited by 911monty; 12-08-2017 at 09:16 PM.
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