Just wondering what the final verdict was on this?

Say going from 2.25" to 2.75" to 3".

Or just 2.25" with a 3" cat back?

Thoughts?

for your eco s/c id go 2 1/2" all the way out

If anything you want to decrease size as you reach the back. The air cools dramatically from the engine to the back and the density drops. Making the pipe smaller towards the back keeps exhaust gas velocity up by countering the drop in density.


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'96 Cavalier Good ol' Pushrod 2.2
-24X,000 miles on factory build
-Some oil loss between changes, me thinks it be rings.

Increasing the diameter of the pipe will also have a megaphone effect, causing the exhaust to be extremely loud, with no gain in performance. Infact you would probably lose peformance, as David Jones stated above.

David Jones wrote:If anything you want to decrease size as you reach the back. The air cools dramatically from the engine to the back and the density drops. Making the pipe smaller towards the back keeps exhaust gas velocity up by countering the drop in density.

The presence of a catalytic convertor would re-heat the exhaust mid-way...assuming he's running a cat. I'm not saying that he should step the sizes up (no way), but a reduction wouldn't be the best idea either.



fortune cookie say:
better a delay than a disaster.

Looking at your registry I would go with a full 3 inch exhaust. Also it says "Reveco 69mm-60mm-62mm Throttle Body" what size is your TB?



FU Tuning

John Higgins wrote:Looking at your registry I would go with a full 3 inch exhaust. Also it says "Reveco 69mm-60mm-62mm Throttle Body" what size is your TB?

That means it was bored 69mm before the plate, 60mm at the plate, and 62mm after. The goal is to increase air velocity.



fortune cookie say:
better a delay than a disaster.

its 69mm at the opening of the tb , not before the plate

but think of it as a hour glass

[quote=97trd(???™)]its 69mm at the opening of the tb , not before the plate
but think of it as a hour glassWhat kind of weird-ass TB do you have where the opening is not before the plate?
Of course it's not right before the plate...that would be an obstruction



fortune cookie say:
better a delay than a disaster.

I don't really want to purchase another catalytic converter...but if the 4-1 Pacesetter header can support a 3" exhaust, I'd look into it.

I want something quieter than my exhaust (not hard) but will also increase performance with the s/c.

So the general consensus is do one size all the way back?

yes....and if you do 2.5 or bigger exhaust and want the pacesetter header get the LSJ header.