Have a '05 WR450F with 2,500 Kms. Running fine in all the powerband range (I think) - 48 pj - 175 mj - 0 leak jet (no bog ) - Stock needle - 1 1/4 fuel screw - AIS mod, grey wire mod. - Air box mod (snorkel out & side cuts) - Stock muffler modded ("Dodjy Mod") - plug color: tan - 0 to 2,000 ft, 60 to 75 'F Have the JD Needles (blue & red) but never have used them. Now I am wondering if changing the stock needle could make a big diference. Better power response ?, more crispy ? If the answer is yes, on account that I am running "zero leak jet", how that influence the decision of using JD red or blue and the clip position ???? Thanks.