I was back at Calsonic, for those who remember, but due to rain we never got in another sound analysis. Their dyno is outside and the rain might affect the sound pick-up. But next trip we hope to get it in to determine the sound difference with header, now that they are installed.

But this time they had a full CL-S exhaust in the shop and it was cut open. One nice thing, it was sitting near a 2000 TL exhaust. So comparison was easy. One immediate difference was that the CL-S exhaust was much straighter. Most of it is nearly a straight path. The resonator is a short, about 8" long, straight through design with a larger diameter chamber. But one point of restriction would have to be the so-called 'Y'. More like a 'T' IMO. But in all I would have to say that 5 FWHP max could be gained from a tuned exhaust.

 

Is there a way to get TRUE dual exhaust on the CL-S? Is there any advantage/disadvantage to this? I would think if each muffler had it's own seperate path from the headers, then that would increase performance?

I am new at this stuff, what do you think?

 

Perhaps, I think the most beneficial thing for an NA exhaust is what Nissan does. Having a valve in the exhaust stream closed at low rpm, for better torque, and then at rpm, opening it up for better hp.

Anyways, I had my car at an exhaust shop just a few weeks ago, and what do ya know, he pretty much said the same thing, Steve. He commented that the Y (T) pipe was restrictive and bad for flow.

And as for room for plumbing two pipes, Well, there's the issue of getting custom headers, cause it will no longer be a 6-2-1. It'll be two 3-2-1's. Also the heat shields under the car are built around the exhaust pipe. Just one exhaust pipe specifically. So you'd either have to take them off, bend them, or get some custom one's manufactured if you want to retain the functionality of them. Also there's fabricating brackets that hold up the B pipe and the resonators. And lastly, and IMO the biggest obstacle, is somehow wiring up the ECU to receive 4 O2 sensors instead of just 2. A true catback has two downpipes, two cats, two B pipes, and two mufflers. Two O2 sensor's per cat, and I don't know how in the world you'd manage to hook up the second pair of O2 sensors.

But don't let that discourage you. If you have enough money you can do pretty much anything you want to your car.

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Kenny
Slow TL

 

There might be small gains in a true dual exhaust system. But the authorities would frown upon this. This would require changing the catalyst system which is a no, no...

Whenever you change the emission detection and controls you have killed any chance to get passed on an emissions test if they do visuals.