Just scrap the white stuff off, dont go in there like a bat out of hell with a chisel, just a gentle scrap with a flat blade screwdriver and maybe a little sand paper. Wouldnt hurt to lightly sand the rota button as well. The best you may get out of doing this is a smoother running motor.
As for the rest of your question.
Nothing you do to the standard equipement will get you more power, you may regain loss power but not gain. Actually you may gain 1-5hp with higher octane fuel, advancing you timing and an exhaust upgrade but thats about it.
If you want more power, search for cams and a ecu package. New thinner head gasket to up the compression a little.