I have a whipple on my truck and i have noticed recently that at part throttle boost goes up to around 5, then slowly decreased to 0 during the shift, then back to 5, then back to 0..... is this normal?

Also, i noticed the other day that my fuel pressure was bouncing around a little. jumped up and down from 50-60psi for a few sec without me moving my foot. WTF? Seems like my low end power has greatly decreased lately and I only seem to have power if i stomp it. Any thoughts? The only thing i changed is the tires, went up to 295/75/16 from 285s

 

nobody has any ideas?