I don’t believe the rules permit removal of any portion of the lower steel valance panel.
The arguments for leaving the splitter allowance in the rules are these:
- it has been in the rules since at least January 22, 2008 (the oldest copy of the rules I have)
- it is arguable (see “Ranger”) whether the piece makes a difference and whether that difference is positive or negative
- to say “it’s not spec” is a red herring that ignores that numerous components affecting the car’s handling are not spec in our series (brake pads/rotors, tire pressure, age of shocks, suspension bushing material, alignment, rake).
- it is a home-build project if there ever was one
My suggestion would be to improve the rule to make its applicability the same regardless of big bumper or small bumper car. Change the language to state the (a) maximum distance the leading edge and (b) minimum distance the trailing edge can be forward the front hubs. Leave in the part about the contour following the overall outline of the body when viewed from above. A plumb bob and tape measure are all the tech tools you need.