i had the same thing happen to my car it had a lot of miles like 220 and it was only gettin like 8 psi with a 3.4 pulley and headers replaced the blower with a lower mileage used one and ported and polished it and i see 11 to 12 all day long in the hot and sometimes 13 when its winter the old blower had all the rotors pealing but im not sure thats what caused it it just didnt like to boost anymore