There are many modifications made to the SCHA, each addressing a known issue.
The stock shift change arm is the biggest weak link. The stock arms are made of poor quality stamped steel, and are often damaged (stress cracked or bent). This piece has been replaced with a heavy-duty CNC machined tool steel arm that will not bend or break like it's stock counterpart. A damaged stock arm often goes unnoticed as the damage can be difficult to spot without disassembling the SCHA and/or checking for proper operation of the internal components through assembly and testing utilizing a windowed transmission case. Many people have damaged part after part and experienced issues shifting without realizing that a damaged shift change arm is to blame. Then, replacing it with another stock unit has resulted in the same problem occurring again, usually within a short period of time.
PRODUCT UPDATE as of 05/17: After a year of successfully testing a new process in our own race cars, we are proud to announce an update that results in an even better product! The shift piece is prone to wear and the interlock is prone to wear and bending as well, which negatively affects the operation of the SCHA and can result in increased difficulty shifting and insufficient fork throw. The interlock is no longer welded and braced - the interlock and shift piece are now CryoHeat treated and micropolished. We've found that this process greatly reduced heavy wear rates seen in these parts, gave smoother shifting action, and reduced shift fork "digging" into the interlock which eventually cases a delay in shift speed and bent interlock.
The SCHA base is TIG welded at multiple points where fatigue cracking and stock weld failure has been seen to create a much stronger assembly that offers more precise, improved shift action and will hold up under the abuse seen during aggressive shifting such as when used in a drag racing application.
In addition to these modifications, the shift select return spring has been upgraded with a much higher tension unit. This gives the shifter a more positive feel, and returns the shifter to the center position with authority. This allows for much easier 2-3 shifts as well as greatly reducing the chances of the dreaded 1-2-1 or 2-3-2 mis-shift, and does not require solid engine mounts to work.
Saving even one missed shift, damage to a dog ring or gear, or reducing damage to a syncro sleeve or the dog teeth on the gear itself is worth it alone. Not to mention a lost race due to a transmission that doesn't want to or won't go into a gear because of a damaged SCHA. The easier 2-3 shift and reduced chance of a 1-2-1 or 2-3-2 mis-shift is a great benefit as well.  
This upgraded assembly is great for those who want to make sure each shift engages as it should, especially under racing conditions, or for anyone desiring a better functioning gearbox with greatly improved reliability!
All Modified Shift Change Holder Assemblies are built to order. This item will ship in 7-10 business days after order is placed. One year limited warranty against manufacturing defects. This does not cover damage from abuse such as a bent base or interlock, or normal wear from use.