If you don't actually need a new pipe, you could get more top by adding
say a .5 mm base gasket and get appropriate head mods. You'd save a chunck of change too.
SLP or RB carb wings. I had a lazy '92 KX250 that responded very well to a wing.
It was the same in a gear for lower rpm's, but if I selected a mid rpm gear
it behaved like a SX bike. I suddenly could leap off small trail objects to
clear this and that. Whole new personality from mid to top.
My fav is hotter CDI map. MC model CDI will deliver the goods. Better
roll-on power under loads, ride a gear higher and way more top-end.
If you ride on the pipe revs will come fast and hard, but performance is
also better when lugging around as well. May find a used one in the
classifieds forum.
You can save time and $ just by going to this no brainer. Reason being,
all trail models are detuned via CDI mapping. You'll get something between
moto and enduro basically.