Been doing some work on a mates evo 7 rs2 , its been to extreme to be mapped , but since then the head warped he tock it somewhere and they fitted a fq 320 head ,, ive just mot'ed it but hes saying its lacking power , today i have presure tested the intercooler and piping etc tested that the dumpvalve isnt leaking and the actuator is working correctly ,, when driving it its initially boosts then looses boost them pulls as the revs rise ??? can this different head fitted cause these problems we dont know if they swapped cams and pulleys etc are they different?? does it need re-mapping again ??