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      03-22-2016, 10:48 AM   #4
Twixboy
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Drives: '04 Z4 3.0i 6spd
Join Date: Mar 2015
Location: MA

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I thought he meant what is the difference between the 06-08 2.5si and the 06-08 2.5i? They both have the N52 engine, but the si puts out 40 extra hp. I'm guessing different intake manifold and a tune. I've never heard of the 2.5i or 2.5si from 06-08 though...
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