As stated above, I don't see any reason why the advanced timing should affect your valve lash. The rattle you hear is detination. It is caused by the timing being advanced all the time rather that just under high load/boost/rpm conditions. Ordinarily the TST will ramp the timing advance in taking into account boost and rpm but you've fooled it into thinking it has full boost so it just gives you full advance all the time rather than ramping it in as the boost increases.
-Scott
-Scott