Primary things I can think of would be more improvements on in general. For racing applications, Like...

1. ECU/computer system improvements. When you turn off traction control the ESP is really off, not just partial. Put the control back in the driver's hands. (not for everyone as people do stupid things and get hurt/killed). Simple Fuel, timing remapping (similar to what Upsolute and RennTech do, but more aggressive).

2. #1 above, pulse larger injectors could be introduced along with an even more aggressive timing curve to allow much more exotic fuels to burn at manageable temperatures.

3. #1 + #2 and ECU reprogram and mild - always on roots style blower change out for more raw horses. (around 10 psi blower).

4. All of the above PLUS swap out the aluminum pistons and rods with forged pieces. (similar to the changes made for the SRT6 engine). In this case the blower could be more aggressive (14 psi or more).

Beyond that, I'm not sure.