There are 600 CFM vent hoods that are designed to work with a 6" duct. I'm not an expert but I believe it's a bad idea to use a smaller duct than the manufacturer recommeds - it will compromise the effectiveness of the hood and create more noise. I'm not sure that you can find a 27" deep hood that will work with a 6" duct, but that's a compromise that you may need to make if you can't increase your duct size.

BIG BIG problems. It won't work, or if you do manage to squeeze things in using that 6" duct, it'll sound like an airport runway with all of the planes taking off at once!

Firepower on your range and ventilation planning are hand in glove considerations. You don't purchase one without the other. Period. Either upgrade your ventilation ductwork and blowers to be suitable for the BTUs you want or downgrade the rangetop to be suitable for the ductwork you currently have.

And, rereading your post, you state "for the way you cook" implying that you don't do much high heat cooking. Well, then, it ought to be a fairly simple choice. Downgrade to a unit suitable to your ductwork!

25 feet is a considerable run even with 8 or 10 inch duct.

6 inch on top of that is way to restrictive.

I'm going to reiterate my original post although others may disagree - 600 CFMs is more than adequate for your Bluestar range - I have a 600 CFM hood (unfortunately only 19" deep) with an existing 6" duct over my 30" 5-burner DCS range and it's more than adequate. Is it perfect, no - in hindsight a deeper hood would have been better but I rarely use more than 2 burners at full blast at any one time and I also mostly only need to use the hood on low or medium. I do get some grease build-up on the outside front of the hood but it's not a big deal. If you want the Bluestar because of the 22K burners then I think you should go for it - you can certainly get adequate venting and you'll be much better off than people who have no venting or a recirculating hood.

And at 695 CFM, Zephyr Hurricane specifies 6 inch minimum duct. I agree with weissman. This site is dominated by those who want the ultimate in appliances. 600 or 700 CFM may not be the be-all, end-all but is it enough? Sure. It's still two or three times more ventilation than 98% of homes have. I've got another idea for the OP though: go ahead and install what you want. Maybe the experts here will be wrong, it'll work fine and you'll have your 1000 CFM. Or maybe they'll be right, the noise will be horrendous and you'll only be able to run on low and medium. But you'll still have the 500 or 600 CFM or whatever your duct *does* turn out to support. The point is, you don't *have* to run the fan on high. The only risk is you will have spent good money on a high performance hood you can't fully utilize. But if money isn't a factor, what the heck?

A very close and now deceased partner of mine used the phrase, "it's not a perfect world".

The comment by markw just above this post has that same thought imbedded in it. I can try it. If it is not acceptable, I will spend the cost of a new rangetop,oven and installation to go from 6 to 10 on my duct run.
Thnks for your help everyone.

Look, I run a Bluestar range without a hood at all, and there are many others here who do the same because they live in apartments or co-ops that don't allow hoods that vent to the outside. It works fine for 90% of the cooking we do. I try to do steaks and fish in the oven with the broiler instead of on top. It's cooking bacon, burgers, and some stir fry items (vegetables just create steam) etc on the top burners that a good hood would help ( to keep the smoke detector from coming on)... Searing steaks is less smokey if you use the broiler instead of a grill pan. And yes, for those smokey greasy items, I open the window and manage. My neighbor has a nice Capital range, and is always cooking and inviting folks over- she has no hood- and cooks amazing southern style foods.

It's not the high BTU's that require a hood, it is the type of food and the style of cooking that determines how good of a hood you need. You can have a small weak stove top and put a cast iron skillet on it till it's hot and throw some greasy meat in the skillet and you'll get smoke galore.

Is a 10" duct better?, yes very much so, when you really need it.

Kobe Hoods have a wide choice of range hoods that are over 700 CFM and 800 CFM that can be used with 6" duct, their hoods are quiet and you have a choice of hoods with baffles or oil cups, oil cups are better for odor removal.