I have a V2 Sti jap import. Recently when driving around the car will randomly decide to go from normal boost levels (14-15psi) to wastegate pressure (about 7psi). any ideas on why this could be happening? No CEL or anything.

The car does however feel kinda of sluggish. Turbo seems to take awhile to kick in. Doesn't feel as fast as it should be.

any suggestions would be grand

cheers