Not really needed man.

Gears don't effect your speedo because the source is at the wheel speed sensors. Tire size will but the FJ speedo is slightly off from the factory and running 33s it's actually closer to actual speed. If you go 35s it may be useful but even then you'll only be off a few MPH so it's you can just tone it down 5 MPH or so if youre worried.

That being said I have no idea if the thing would effect your odometer which will also be off if you change tire size.

 

I do run a 35" dia tire so I'm off by about 6 mph at higher speeds. I'm looking for more accuracy for calculating fuel milage and distance traveled.

 

Since there are so many legalities around changing odometer readings I kinda doubt anything will do that. Best just to find the % size difference you are over stock then multiply by that when you do you mileage.

IE with my tire size I know I'm 3% off so I have to increase the mileage from my last tank by 3% before I do the calculation if I want an exact reading.

 

More inputs on this please?

I just bought one (no specific model mentioned in the vendor site) before I read on the packaging that its only up to the 2010 FJ model.

TIA

 

Update:

Manufacturer confirmed that "we do not have anything to work on the 2011 and newer models".

 

My FJ is 2-3mph off with 33's, GPS measured, to do an actual 70mph, I'll have to be driving at 67-68mpg according to the cluster, just get a GPS, measure your speed and compare to your dashboard, you'll be saving $200