Are any of these mods legal in stock?

["Jim Lange" <JLANGE@us.oracle.com>]

Would any of the following changes to my BMW M3 coupe be legal in stock? 
 
1. Underbody X-brace            (stock part for M3 convertible) 
2. Short shifter                (stock Z3 shifter) 
3. Two-piece rotors             (stock on European M3) 
4. Revised cool air ducting for brakes 
 
The last two items are primarily for BMW driving schools (road course driving) 
since the stock M3 rotors are prone to warping. 
 
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Jim Lange                               '95 BMW M3 (A-Stock) 
Bothell, WA