Why does the t.p.s on my rb3 only register 61% WOT?

[kuvasz]

I recently purchased a rb3 and i just installed it and got it working on my sled. It's a 2008 apex ltx gt. Now for some reason the throttle position sensor will only read 61% when the throttle is wide open, why? shouldn't it be 99% or am i missing something?
I have 3 different maps for the rb3 and they all say 61%. There must be a way to change it from 61% but i don't know how to do it.
can anyone help me out?