paxon sn boost loss

[Mustang lover]

Hello, my name is Brian Baker from michigan. I have a paxton sn 2000 i believe. Its seems to have lost some boost. If I jam the gas down in first gear i get around 5-6 pounds which is good. Then when I shift into 2nd gear i lose 2-3 pounds. and it hangs around three psi, no matter how high the rpm. Im new to the high performance end of things so im curious if anyone has any idea's as to why this would happen?!?!?!? Im very lost:freaks:

[speedytang]

Belt slipping.