Those 300s have the great GP racing sound to them! They usually require the needles be raised a notch if you had HM341 pipes before, or else raise the mainjets a 5 size. Most of the 300-piped K1 bikes had 115 mains with the needles in the center notch until the spark advancers dropped a few degrees, then they got 110 mains with the clip moved down to slot #4 on the needles.
Overall, the tradeoff is about 2 HP at 4000 RPM: the engines loses 2 HP at this speed, but makes 2 extra HP at 8000 RPM in the tradeoff. The 341 pipes came out when the U.S. speed limit dropped to 55 MPH and the from countersprockets went to 18T instead of 17T, and the pipes helped boost the torque right where most riders ran. It also make them a little quieter at 70+ MPH behind fairings, which is what made me buy the K2 in the first place, trading in my K1.