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17/8, 117/8 stepped, 2" ????

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Old Dec 12, 2009 | 03:43 PM
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Default 17/8, 117/8 stepped, 2" ????

LS3.4 (417) 11.0 to 1, Tony M. Ported 205's, Vengence ported 92/NW92 and 238/246 at .603/.606 115+4.

I have 13/4 now. So going to 17/8 would mean I could use existing ORY. Stepped 17/8 or 2" have 31/2" collectors, so thats another $400.00

Any thoughts.

This is a daily driver set up to be strong on the bottom.
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Old Dec 14, 2009 | 07:28 AM
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The only way stepped header really show their stuff is when there's no back pressure behind them. The stepped change is cross section is designed to enhance velocity through the exhaust. This is somewhat negated when you add a closed exhaust. My advice, if you're after big numbers, go with the larger headers and the larger collectors, then neck them down to 3" duals as soon as you can. You should be able to adapt them to your current y-pipe with minimal cutting. Hopefully, your current mid-pipe is dual 3" already and has a 4" y-collector and 4" cutout. If not, you're not going to see much of the gains of the larger headers due to the downstream restrictions.
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Old Dec 14, 2009 | 03:44 PM
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Ron at Vengence wrote this PM

"Good to hear from you sir.

My suggestion is 1 7/8 with your current 3" Exhaust. Anymore primary size is overkill for your combination.

Let me know if we can help you out."

Still looking for opinions! the more the better!
Ed

Ron
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Old Dec 14, 2009 | 06:10 PM
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I have 1 7/8 stepped headers on my motor. I know of another almost identical motor that made almost the same power (slightly higher) with 1 7/8. I'd take Ron's advice unless you have plas for FI or a lot of spray.
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Old Dec 15, 2009 | 07:11 PM
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Default PM reply I post these here in so maybe they can help others

Ed,

In testing in the past I haven't seen huge differences between 1 7/8" and 1 7/8"-2" stepped headers on an exhaust with mufflers and long extentions. Basically, the point is that the step can move your torque curve and SOMETIMES give you a broader power band, however it is highly application dependent based on cam, cubic inches, downstream exhaust, etc.

In other words there is no 'right' answer other than testing for your particular combo.....

I think either pipe size will work fine for your needs.
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Old Dec 15, 2009 | 07:12 PM
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Looks like the smart money is on 17/8.
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