I can only speak for the Yellow Box here...it does not affect the tach in any way. I think this is good...I want the rev limiter!!
Also, the '01's (and probably the '02s) were speed restricted based on the signal from the speedo sensor - located at the front sprocket. The ECU calculates speed based on how fast the front sprocket is turning...hence the major speedo error when you change gearing.
So, the Yellow box can effectively "force" the speedo to read much lower than actual speed = derestricted. The only problem is that lets say your running a true 200mph, depending on how you have it set up the speedo will only show 175, 180, etc. You'll have to know the actual gearing of your bike and the offset for the Yellow Box to give you real speed.
It's all fairly simple math really...only hard to explain!! My estimate is that the YB should theoretically allow you to go over 215MPH, depending on your final gearing. Any takers?? If so, I want to be there for it!!!!!
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