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I'm thinking about doing some exhaust mods to my 83' 280zx non turbo 5spd. I'm thinking about adding bigger pipe, 2.5 I was wodering what way would be the best way. I thought of a couple different ways.
1. 2.5 pipe from stock downpipe to a flowmaster
2. 2.5 pipe from cat. to flowmaster
3. or the most expensive way, 2.5 from stock
downpipe to free flow cat, to flowmaster.

I live in florida and we only need visuals on a cat. and I've talked to someone that has
done dyno tests and found that a stock nissan
cat. doesn't cost ANY HP.
So would option # 2 be the best way?
Thanks for your help.
--Casey
280zx
 

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> I'm thinking about doing some exhaust mods
> to my 83' 280zx non turbo 5spd. I'm thinking
> about adding bigger pipe, 2.5 I was
> wodering what way would be the best way. I
> thought of a couple different ways.
> 1. 2.5 pipe from stock downpipe to a
> flowmaster
> 2. 2.5 pipe from cat. to flowmaster
> 3. or the most expensive way, 2.5 from
> stock
> downpipe to free flow cat, to flowmaster.

> I live in florida and we only need visuals
> on a cat. and I've talked to someone that
> has
> done dyno tests and found that a stock
> nissan
> cat. doesn't cost ANY HP.
> So would option # 2 be the best way?
> Thanks for your help.
> --Casey
> 280zx
Casey, If your not going to add a header the gain is not worth the expense. With the header you need to use 2 1/2 all the way. I will tell you that flowmaster is loud as ****! I know, I have one.

Good Luck, Bret
 

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> I'm thinking about doing some exhaust mods
> to my 83' 280zx non turbo 5spd. I'm thinking
> about adding bigger pipe, 2.5 I was
> wodering what way would be the best way. I
> thought of a couple different ways.
> 1. 2.5 pipe from stock downpipe to a
> flowmaster
> 2. 2.5 pipe from cat. to flowmaster
> 3. or the most expensive way, 2.5 from
> stock
> downpipe to free flow cat, to flowmaster.

> I live in florida and we only need visuals
> on a cat. and I've talked to someone that
> has
> done dyno tests and found that a stock
> nissan
> cat. doesn't cost ANY HP.
> So would option # 2 be the best way?
> Thanks for your help.
> --Casey
> 280zx

Remeber to check the archives, when searching for a solution to a question like this. There are many posts in the past, about this very problem.

Good luck. I'm currently in the same situation myself. I can't decide what to do yet. I'll probally end up with a 2.5 pipe from the manifold back to a Flotech Afterburner muffler. I have the casing for the cat, but somehow or anothr, the insides have disapeared. Mmmm. . .must be the Z fairy.

Chris Behney
Redline Autosports
 

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> Casey, If your not going to add a header the
> gain is not worth the expense. With the
> header you need to use 2 1/2 all the way. I
> will tell you that flowmaster is loud as
> ****! I know, I have one.

I second this motion. The flowmaster is loud. Look into something like the Dynamax ultraflow or similar. I say For a mostly stock application, ie no cam, port work, etc..., run a downpipe from your stock manifold I say 2.5, since unless you have mandrel bends, you are reducing the internal dia on the 90 bends at the back of the car, so effectivly, you are running smaller than 2.5. I personally run 3, but I have a heavily modified motor. An ITS racer,(someone who has to race with a mostly stock motor), did some dyno testing with stock manifolds, vs headers, etc... and he found that the stock manifolds perform very closely to aftermarket headers for a stock application. You can buy a header, but it will mostly just make your car louder, not add power. But if you start adding other things, then you will start to see a difference.
-Bob Hanvey
 
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