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There are several guys out there running D1s in their cars. And a few LTx equipped C4s are running D1s as well. For the street I personally wouldn't want to run any more than 14 PSI of boost. Any more than that and you will be running race fuel in the car. The need for an intercooler at that range is also highly advisable, either custom made for the car or otherwise.
I presently run between 8 and 10 PSI with a upgrade to a T Trim Votech sometime this year which would put me up to 12 PSI with an intercooler. That is the maximum I will ever plan on running on the street with pump gas. The reason I am going to a T Trim is that the T Trim produces 12 PSI of boost a much lower impeller speed than the S trim therefore making it more efficient which means lower outlet temperatures which translates to more power.