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      12-04-2012, 12:29 AM   #19
Munit
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Drives: m3
Join Date: Oct 2012
Location: CA

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These are one of those situations that if you simply step back and use common sense you will see that its really not sensible that bmw M would use a restrictive elbow if there was 10hp on the table from using a slightly larger diameter pipe. The diamter being smaller is not necessarily more restrictive. Its likely calculated based on desired intake air velocity whichi requires a certain diameter. Larger diameter means slower moving air. So while it may move "more" air, the air is slower and would take more time. This intake does not have a restriction for air in totally stock form.

Evidence is in the GTS 4.4 stroked engine which uses the identical intake box as the stock s65 m3. Clearly a 4.4L if anything requires more air and the stock setup provides enough air for that so our stocker engine has more than enough air.

I think a dyno gain is for the filter only but to each his own. M would not leave 10hp on the table if it were a matter of tweaking the intake elbow diameter. Just makes zero sense