Yes stock is 430's, I ran 420's all season, even at -6F and no problems.Plugs and wash looked good. I put a Black magic single on this thing and it was slower than stock, they say the single hurt this thing more than help it. I ran against 4 F7's with the pipe and trailed all the way, threw the stock pipe back on with some clutching and kicked all of there butts, go figure. I added an after market head and V-force reeds. The best change I made was a 1.5" track, no more sitting and spinning on take-off, and believe it or not, no loss in top end.