My idea of the best cat/y-pipe design..not currently made
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From: Kansas City
My idea of the best cat/y-pipe design..not currently made
I've been thinking about this for a while now. It's well documented that the 02-03 VQ35 Maxima/Altima makes healthy gains (~20whp/25wtq) with headers. The Maxima/Altima VQ35 is equipped with two precats on the exhaust manifold and one main cat after the y-pipe. When adding headers, the precats are removed and the precat 02 sensors are moved downstream behind the main cat as not to throw any codes. It's well known in the Maxima community that the precats are fairly restrictive and that removing them adds 12whp. The cat itself doesn't prove to be much of a restriction at all.
The G/Z VQ35 utilizes a precat and cat sandwiched together just south of each exhaust manifold.
Here's my idea:
You make a combination testpipe/y-pipe that is all one piece with some nice mandrel bends for the bling-focused guys. Then shortly after the Y junction, you install a single 2.5" ID high flow cat. Just after the cat, you'd have two bungs welded in for relocation of the O2 sensors. This design would require extending the Y-pipe pipe length into the midpipe therefore requiring a slightly modified midpipe to make room for the cat. You'd also have to extend the 02 sensor wires.
This setup would do a few things:
1) Take away the initial restriction right after the manifolds.
2) Reduce exhaust system weight by ~30lbs.
3) No more aftermarket cats hitting the OEM heatshields.
4) More power? I'd say an easy 12whp/15wtq
The downsides:
1) Fairly rich fuel smell upon cold starts. After the cat has warmed up the car shouldn't smell.
2) Potentially fail Cali/NE sniffer tests
3) Some additional exhaust noise, though the large cat and stock resonator should quell most of the annoying rasp and any drone.
What this y-pipe/cat layout is emmulates the exact aftermarket y-pipe setup available for the 95+ Maximas. These setups were good for an honest to God, tried and true 12whp/15wtq on the VQ30s. I'd imagine the VQ35 should see fractionally more power. I know that adding my Y-pipe to my 96 Maxima dropped my ETs by .2 and gained me over 2mph in the 1/4 mile.
The G/Z VQ35 utilizes a precat and cat sandwiched together just south of each exhaust manifold.
Here's my idea:
You make a combination testpipe/y-pipe that is all one piece with some nice mandrel bends for the bling-focused guys. Then shortly after the Y junction, you install a single 2.5" ID high flow cat. Just after the cat, you'd have two bungs welded in for relocation of the O2 sensors. This design would require extending the Y-pipe pipe length into the midpipe therefore requiring a slightly modified midpipe to make room for the cat. You'd also have to extend the 02 sensor wires.
This setup would do a few things:
1) Take away the initial restriction right after the manifolds.
2) Reduce exhaust system weight by ~30lbs.
3) No more aftermarket cats hitting the OEM heatshields.
4) More power? I'd say an easy 12whp/15wtq
The downsides:
1) Fairly rich fuel smell upon cold starts. After the cat has warmed up the car shouldn't smell.
2) Potentially fail Cali/NE sniffer tests
3) Some additional exhaust noise, though the large cat and stock resonator should quell most of the annoying rasp and any drone.
What this y-pipe/cat layout is emmulates the exact aftermarket y-pipe setup available for the 95+ Maximas. These setups were good for an honest to God, tried and true 12whp/15wtq on the VQ30s. I'd imagine the VQ35 should see fractionally more power. I know that adding my Y-pipe to my 96 Maxima dropped my ETs by .2 and gained me over 2mph in the 1/4 mile.
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Rhinos7777
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Sep 6, 2015 05:36 PM
