430 is a great engine, strong & torquey but revs better than a 500. A bit toey with CR internal rotor ignition for me, I run WR or XC ignition with 13/53 final gearing on mine. I have a Mossberg reed valve, Pro Form pipe with modified KX500 muffler on the current bike, it's strong but super smooth, just the thing for a fat old bald bloke like me! Love the 430 engines.
Cheers,
K