Speedometer correction

[Mark57]

I installed a leveling kit on my 2024 sierra 1500 and was waiting for Rough Country to release there speedometer correction, just saw they did last month, wow $900.00.  Has anyone tried it need to get one my shift points are all off, any input would be apricated thanks.  MARK    https://www.roughcountry.com/product/speedometer-calibrator-90050?utm_source=google&utm_medium=cpcs&utm_campaign=18022125814|&utm_content=&utm_term=||c||fit_first_90050-b&gad_source=1&gclid=Cj0KCQjwjY64BhCaARIsAIfc7Ya1fBNfVab1cBnuIRHpEcr_Gb_9z47VTGbDRV2ONeFpHHfkXjlu0bUaAl30EALw_wcB                             

[KinkyDuramax]

If you've leveled a Truck I feel like the speedometer is off 1-2mph, I think for it being $900 I'd rather just deal with it being inaccurate by 1-2 mphs. I feel like at that price it should do more, like a pulsar lt

[AJMBLAZER]

Was wondering how far off the speedo is?  I've got 33-34" tires on in place of the 31.something tires it came with and I'm only 2 mph slow at 60 and 3 at 75.  Trans shifts fine.

[Mark57]

My radar detectors GPS and my Navs GPS shows 4-5 MPH off.  When I drive 74-80 I have to over shoot my MPH  by the 5-7 MPH in order for my shift point to shift into OD.

[Agent 409]

this is a website that tells you how far off your speedo is if you do the comparison tool. 

https://tiresize.com/calculator/