the 320 should be able to utalize any part from any of the other i6s. To dramatically increase power, all of the following could be done without going to a supercharger or turbo.
performance ignition coils
All of those will create more power or reduce the amount of power needed to move them, thus increasing speed.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>