Sorry to hear that, that is one of the reason why I am hesitating to go for the stage 1 pulley.
Mine does it aswell, the idle should be solved by the closed loop feedback system. The engine light is because of the catalyst removal. The flashing TRC appears when you get near the rev limiter. There is no risk involved in it as far as I know, my car has done about 15k miles since all fitted and it is still running
I am running 0.45 with the standard pulley. When the stage 1 was first fitted, it produced 0.65 with the Katana intercooler
And yes, Lee's produces nearly as much power as ours with an almost standard TTE supercharger