My 83 Turbo ZX manual says that all timing advance curves are adjusted by the computer according to factors like engine load, throttle valve angle, intake air temperature and density, and engine RPM, so I'm not sure that adjusting the timing manually at idle will give you any noticeable improvement in power. I do know that I put a Nitrous Oxide kit on my Turbo Zx, and drilled a tiny hole in the vaccum line going to the wastegate valve actuator, this increased my boost considerably. My only problem is the Pressure Relief valve on the intake manifold is letting some of this excess boost pressure go straight out of the intake manifold. It does'nt really matter to me though, because I still have a Sh*t load more horsepower and torque. I beat most slightly modified Mustangs in the quarter-mile because my car is so much lighter than theirs. Also, the nitrous acts as an intercooler too, adding even more power! My best time is 13.8 at 103 MPH, it's not too bad.