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ST5 Modified Front Bumper rule clarification


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Please help me clarify the ST5 front bumper rules.

For cars not taking the BTM aero modification factor, the rules read as follows:
"3) Modified BTM, non-Base Trim Model (non-BTM), or replaced front fascia (unless specifically approved in Appendix B:
i) May have nothing attached to it other than specifically allowed items (above).
ii) May not have canards/winglets molded into it.
iii) Any item that is molded into the fascia during the original manufacturing process that functions as an airfoil, deflector, dive plane, or vortex generator and extends 2" or more past the outline of the immediate surrounding fascia is prohibited. To inspect: a plumb line run across the entire surface of the fascia and bumper shall not have any such item that extends 2” past the line when viewed from above."

To me, item iii above is self contradictory.
"2 inches past the immediate surrounding fascia" and "2 inches past the plumb line when viewed from above" are different.

Here is my example, a very common aftermarket Maxda RX8 bumper:


So the question is, how do I properly determine the legality of this bumper?

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It's a little confusing because it says to run the plumb line over the entire surface of the fascia--which would include the "immediate surrounding fascia" as shown by your arrow.  It doesn't say to take a plumb line from the most forward aspect of the front fascia or "outermost edge" as your other arrow shows.  So, if that dive plane (correct on that) is sticking out more than two inches from the immediate surrounding fascia as you show, it would not be a permitted modification for ST5.

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The "plumb line" verbage is confusing, because its not physically possible to use a plumb line to measure anything other than the outermost edge.  But I get the meaning now.  Measure with a perfectly horizontal ruler to the immediately surrounding fascia.

If it's illegal, I suppose the bottom portion of this bumper could just be cut off, and replaced with a vertical airdam extension.


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