I have t-6's, I love them. I can only compare them to my old fmf gold series, the t-6 pipe comes in lower and pulls higher. My buddy has my old pipes, our mods are basically the same and I tear him up. I also heard the t-6's don't work well with a ported motor.
I would increase the pilots a couple sizes, should help your holeshot and starting. Also i would increase the main 1-2 sizes, should help you pull sixth gear.
I had the same problm, mine turned out to be the coil connection. I sodiered a different type plug to the coil and in the harness,then siliconed the whole coil. No problems since.
I traded my odessey for my banshee, Crazy. my odessey diden't manuver well, power wasn't great, and the suspension will beat you to death. check into a kfx 700 easy to ride, good power, good handling. My wife loves hers.
If you ride mostly dunes stay with the banshee.2-strokes are easier to work on for me. Theres no valves, no chains. none of extra parts on 4-strokes. Acouple of months ago dirtwheels compared a new banshee,yzf, and raptor.they said the banshee is still king of the dunes. Mods on a banshee are easier to get more h.p for less $ and stay together. If your going to ride trails or track the yzf may be better because of the user friendly powerband.
There could be many problems. Iwould check compression, One side might be a little wore and take longer to warm up and seal. check your carbs,clean if needed.
When I switched from the old fmf's to the t-6's, My holeshot improved, I was faster out of the corners, and I have more top end. I'm thicking about gearing up to a 15 tooth front. I love my t-6's.
I have t-6's, They have way more power down low compared to my old fmf's. my head is milled 30, v-force reeds, 4-degrees timing, trinty cv intake 38mm carb.power comes on hard and low but also pulls higher than the fmf's. no problems in the trails.