Can't help you out with any numbers or dyno charts, but I do have the S1 Dinan package on my 06' 4.8is. Personally, I think its great. There is noticeable power gain, esp off the line and throttle response is awesome. I'm already pushing 75k miles and has had no problems with the package. Dinan is reliable and I would recommend it. I think turbos and superchargers are unheard of for the 4.8is...unless someone can prove me wrong, I'd love to see that but never have.

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06' E53 Dinan X5 4.8is
01' S54 M coupe
-Elliot