Modifying the air return ducts?

Hello,
We're currently redoing our kitchen in a 1000sq ft., two story townhouse, and thinking about removing about couple cubic feet of duct. I'll try to explain it as best I can:
Our air return duct goes straight down from the 2nd level to the basement, at mostly the same dimensions the entire length. However, once it gets near the kitchen floor, it increases in depth from about 12" to 18", and continues at that depth until it hits the furnace. On the opposite side of the wall (living room) is a return vent, and this is where the dimensions change. The return vent is about 6" wide, and the ductwork is about 8" wide- no problem there- but at this point it goes from about that 12" depth to 18". I was wondering if this is done for any particular reason, because we'd like to remove the extra depth in the kitchen area to allow for a cabinet. The return would only be modified for about 2 feet, and the rest of the return would remain intact.
Is there generally any things to watch out for, or does this seem like a non issue?
thank you!! Frank
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posted for all of us...

asked in alt.home.repair and get a pro to do it.
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Tekkie Don\'t bother to thank me, I do this as a public service.

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Tekkie wrote:

This is actually helpful. Maybe the folks in alt.home.repair won't need to belittle posters in order to reward themselves for the knowledge they have.
Actually, I got my answers from this group by careful discernment amidst a barrage of sarcastic responses.
Esoteric - Hidden or deeper knowledge or teachings that are possessed or understood only by a few. Hmmmm...somehow I think H.V.A.C. theory wouldn't be described by this word.
The subscribers of this group may not reveal the amount of knowledge they have, but their level of intelligence and humility is communicated clearly.

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snipped-for-privacy@gmail.com wrote:

if the kitchen cabinet is more important than the performance and efficiency of your heating & cooling system, go ahead and whack the return air ductwork.
An intelligent person would call for the services/advice of a local professional who has the ability to see things first hand, rather than rely on the opinions of strangers on the internet.
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