In the Quest for more Power

I have run power core 2 and turbinecore 2 and can't tell the difference.

You probably need a spark arrestor to ride in SF or NF? That would lead you to the Turbine Core or Q if you are buying FMF.

I have the FMF Turbine Core 2 and the FMF Gnarly "woods" pipe on my 2003 KDX 200. The silencer/spark arrestor (turbine core2) is about 125.00 or so. The bike has tremendous bottom end; almost four stroke-like. The performance of both is wonderful. The Turbine core 2 is us forestry approved. The silencer is very quite surprisingly. Don't forget to loose the snorkel on the air box lid if not the whole lid. I just removed the snorkel and the power is great, without having a wide open air box for water to get in. Any more questions about the combo, let me know... R. Shane

I have the -35 and -30 FMF (woods and rev) pipes as well as the TC (1) and 'Q' silencers. The TC is louder than the TC II, which is louder than the 'Q'. My preferred combination is the -35 with the 'Q'. I could tell no seat of the pants difference in power between the TC and the Q. You'll need to lean things out after the pipe change. I, too, would suggest ditching the snorkel, but keeping the air box lid on. I couldn't jet the bike decently with the lid off.

rear sprocket change helps a lot.

What size rear sprocket are you using? I'm trying a 46T (47t stock) for smoother power in the woods this year.

I finally have my KDX to where I want it but I wish I had followed Jeff Fredette's advice and I probably would have saved some cash. I went with a Pro Circuit pipe and a PC spark arrester as well, I installed a Boyesen Rad Valve at the same time so I can't say for sure which one made the biggest difference but the power delivery was kicked up several knotches in the low end area without losing much on top. I went to a 12 counter sprocket and that gave me even more down low and I really didn't care about losing a bit on top because tight woods around here aren't a top gear priority. The airbox cover is now just a shell and I threw in a Uni Filter since they're supposed to be more free flowing. My jetting for warmer weather -I went down to a 152 main and a 45 pilot, opened the air screw to about 1 3/4 turns out and went down one clip on the stock needle. You'll have to jet for the conditions in your area but that's what I went with for 70 degrees on up at near sea level. I change the top end every season even though I could get away with going longer, I always go with Wisco but if you're just re-ringing it go with OEM or Pro-X which is closest to stock. Don't re-ring your cast OEM with Wiseco rings. The KDX is a fun bike now and a perfect compliment to my 520SX.
I could have saved some money by leaving out the Rad Valve and just going with the Boyesen Pro Reeds. I also hear that the FMF set up mentioned above is a good choice.