17/22 is not really that big of a turbo for a 1.9 like they used to be considered. You can also go bigger than the 2056 already mentioned (funny, but the poster first mentioning it has a bigger 2260 but still said 2056 as the answer to 'biggest' single
). Then in your second post you are concerned about expense? "How big of turbo" you can run, or the compounds you mention should not be considered on a budget basis. Neither goal will be inexpensive by hardly anyone's standard. I'm thinking that if you were heir to a banking or oil fortune, you would not be mentioning expense in the first place
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Point is that the turbo cost is only a minor part of the expense of such a build. If the Darkside kits seem expensive to you, you might want to back away from the diving board and get comfortable in the shallow end of the pool first.
I am a fan of analyzing power cost ratio with my customers build plans - 25 HP costs X, 50 HP costs Y, 75 HP costs Z, and so on. Some of the best value is found in the first 50 HP. After that the value ratio changes exponentially in a less favorable direction.
Just my 2 cents...