Rally exhaust-evo jetting

fitting a SIP EVO exhaust to a standard Vespa Rally 200, do i need to upjet the standard carb and change the spark plug.

thanks for the advice.

a 120/122 main should do it and go to a b8 plug.change the emulsion tube and atomiser to .be4/5 and 190

stroud valleys(midnight hour)sc est 1984

Yes do this, because the engine will run too hot, if you don´t do it.
Start by jets with 10 numbers higher and go slow down, till you have the best result. Spark plug should be one number colder.
Than it must go.
Cheers Daniel