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Exhaust restrictor best option??

cattz

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On my VS V6 it's currently got the Catback 2.5" system.
Now i've read that the standard exhaust is best for fuel economy and torque around town, wher as the 2.5" free flowing exhaust is better for fuel economy on the highway.
It has been suggested that i get a free flowing 2.25" exhaust so i'll get the best of both worlds.
NOW as $$ are not at a premium and i've already got the 2.5" system, would i be able to put a 2.25" restrictor plate in the system somewhere, to get the desired performance of a free flowing 2.25" system, in both city & highway, OR is this a waste of time?
Bearing in mind i've also got the standard 2.25" system hanging up in the shed.

Thanks in advance.

P.S. I've got a 2 hole airbox with K & N filter and no other mods.
 

Jonah 101

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It doesn't work like that. Anyway the only person who will notice the difference in power between a 2.25 and a 2.5 is the man operating the dyno.
 

Drawnnite

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if you really wanted.
just get the standard system put on, and get the mufflers swapped to less restrictive ones.
probably the easiest solution if you really want to do it.
 

cattz

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if you really wanted.
just get the standard system put on, and get the mufflers swapped to less restrictive ones.
probably the easiest solution if you really want to do it.

Would i be correct in saying then, that it's REALLY not much difference in Torque & Fuel economy loss, well not enough to worry about anyway?
 

Andrew426

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Dont do it. Just dont do it.

If you are driving your car around thinking "well, this goes pretty hard, but I think it would go better if I reduced my exhaust diameter by ~6mm" then you are either:

A). A genuis capable of modelling flow and helmholtz resonance entirely in his head, in which case you wouldnt be asking here.

B). The sort of person who believes things he reads on the internet.

Dont forget mate, most of these things you read on car enthusiast sites are written by people no more qualified than you are yourself.
 

Drawnnite

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yup. as Andrew has said, its completely not worth it for whatever minimal gains may be had.

unless of course. you want to blow some cash :p
 

cattz

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O.K. Thanks for the replies.
I'll just stay with the 2.5" and leave it alone.
Cheers
 

Drawnnite

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however I guess seeing as you still have the standard system there
you could always just chuck that on and have a play around with it.

in the end it wont cost you anything, just a bit of time and elbow grease.

and good plan :p
 

Not_An_Abba_Fan

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The money spent on optimizing the exhaust for economy gains will out weight any saving in fuel anyway. You will spend all that time and maybe a bit of money to save less than $3 per 100 kms. The best way to save fuel is to be a little ligher on your right foot when accelerating. And use cruise control whenever you can.

The other way to save fuel would be not to buy a Commodore to begin with.
 
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