Yeah, it is. Even more applicable is that company is willing to do some custom fabing!
Edit, I did a bit more reading on the ruling. As it turns out, NACA ducts can only be used for driver cooling or venting on the hood (but you take a modification factor cut for it in hp/wt calculations). The holes in that strafe design also wouldn't be allowed in a TT4 car. However, Their splitter looks interesting, and they're willing to fab stuff, so maybe I can get them to fab a wing that uses some integrated mounting points.
Here are the rulings for anyone interested:
BTM Aero (adds 0.4 to the to wt/hp ratio):
6.3 ST4 and ST3 Production Vehicle “BTM Aero” Modification Factor
ST4 and ST3 Production vehicles that maintain the unmodified Base Trim Model (BTM)
body lines, do not have non-BTM aerodynamic aides or modifications, and do not have
a rear wing or rear spoiler or rear diffuser may assess the Modification Factor for “BTM
Aero” in calculating the “Adjusted Wt/HP Ratio”. Under this specific rule, an
aerodynamic aide is considered non-BTM if it did not come configured on the base trim
model (BTM) of the vehicle from the manufacturing factory. Except for those vehiclespecific higher level trim models (non-BTM) listed in Appendix B, there is no updating or
backdating across trim models or the addition of dealer installed options permitted.
The following are permitted allowances/modifications for vehicles taking the
Modification Factor assessment for “BTM Aero”:
1) Flat undertray/belly pan forward of the centerline of the front axle, extending
no lower than the bottom of the front fascia..
2) Removal of a convertible soft top/frame and/or adding a hardtop to a
convertible provided that the hardtop uses a sealed rear window and is either
OEM, an OEM option, or the same shape and size of an OEM/OEM option
top.
3) Lexan front, rear, and rear side windows without uncovered holes.
4) Front wing window/frame removal and/or replacement with Lexan.
5) Hood replacement/modification for venting and/or weight reduction (“aero”
hood pins are permitted).
6) Removal/cutting/drilling of the fascia for engine cooling, air intake, brake
ducting, and transponder mounting purposes.
7) Removal of rain gutters/drip edges, windshield wipers, and mirrors.
NASA Super Touring (ST1-4 & SU) Rules 2019 v13.2 Page 11 of 27
8) Rolled or flared fenders (includes add-on flares--only to the extent necessary
to cover the tire as viewed from above—not viewed from the front or rear)
9) NACA ducts, air ducts, or air hoses placed in a side window frame solely for
the purpose of driver cooling.
10) Headlamp, headlight covers, and fog lights may all be removed. The holes
may be left open, used for brake ducts or engine air intake, or must be
covered with material that replicates the shape of the BTM light/cover, leaving
the shape of the BTM fascia intact.
TT4 specific Aero rules beyond BTM (assessed independently):
6.4.2 ST4 Aerodynamic Modification Restrictions and Limitations
If not using the BTM Aero Modification Factor, aerodynamic parts/devices/aides
shall be limited in ST4 to the following:
1) All of the items listed above in section 6.3 “BTM Aero” Modification Factor.
2) Vertical front air dam (5º tolerance) that follows or extends beneath the
outermost edge of the front and side bodywork/fascia.
3) Single flat, horizontal front splitter that protrudes no greater than 4” from where
it intersects with the fascia or air dam. Along the entire splitter, there must be
at least 1” of fascia or air dam material above/superior to where the splitter
intersects the fascia/air dam, including at any air intake region.
4) Single rear wing or spoiler that does not exceed a height of 8” above the roof
line, or width greater than the vehicle’s body width, or end plates greater than
12” in length or height, or 12” protrusion from the rear of the vehicle. Body
width does not include flared fenders, mirrors, splitter, door handles.
5) 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.
NASA Super Touring (ST1-4 & SU) Rules 2019 v13.2 Page 12 of 27
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.
6) Cutting/removal of the rear bumper cover/fascia where it does not cover the
rear frame/bumper cross beam.
7) Complete removal of both the windshield and windshield frame is permitted on
OEM convertible top vehicles, but will be assessed the Modification Factor
listed in section 6.5. The OEM cowl may be replaced with a flat cover
between the hood and the dash, but no air deflectors may be added, and the
entire cockpit must remain uncovered.
8) Convertibles may use aftermarket hardtops that are not compliant with 6.3.2
above, but they will be assessed with the Modification Factor for
roofline/shape, may not extend rearward of the front edge of the OEM rear
decklid, and the OEM windshield frame location must be preserved.
When i first got the car though, god damn it was annoying.