Just looking for conformation on whether the timing on a PX200 should be retarded from 23 degrees back to 18/19 degrees once you have fitted a sip road 2 pipe.
It is not recommendable to change the timing because of a different exhaust if you did not modify anything else on the engine.
You propably need to modify the jetting of your carburetor. Therefore you can perform a classic jetting procedure.
According to the setup of your engine you may find that you only need a bigger main jet, but please also check the size of the slow running jet.
A timing change might be required if you mount a tuning cylinder and/or a crankshaft with a longer conrod.