why turbocharged the stock 660cc engine? just swap de engine out wif a L2/L5 engine... that wud be more ideal than turbocharged it... unless ur's a 850cc and thought of turbocharging it will gip it more torque...
plus de cost wud be alot cheaper... and de power gain are very much diff... u can feel de power right away on the first time drive since de stock 660cc... and i bet sooner or later, u'll felt not enuff power coz' can't yum yum any 1.8 on stock... hehe...
power is upgradeable depends on ur RMs...
;)