Even 9500 RPM might be daunting. Take the Honda S2000 engine. Honda claims the 2.0L version has a higher piston speed than Honda's F1 engine!
When they enlarged it to 2.1L by increasing the stroke, they had to cut 500RPM off the redline. So going up 1000 RPM, on a motor that's undersquare, well... where there's a will, there's a way, but it sounds real expensive.
I would think turbocharging would be the way to go, because while it is more complex, there is more freedom in where you can locate components like the turbine. Lotus getting 300BHP from a supercharger would be amazing.
Consider that a Jaguar XJR "only" gets a 100 BHP supercharged boost, from a 4.2L V8 running .8 bar. This is using a M112 supercharger which has a displacement of 112 cu. in. That's a supercharger with a displacement as large as the host Toyota engine itself!
If the "super" Elise/Exige gets rid of the trunk, then there's lots more room for power adding goodies...
DLY