The basses I have now (an old Warwick, a new MM and a bitsa I built 20 years ago) all seem to be determined to stay in tune, no matter how hard I hit the strings... same thing with the non-trem guitars I own. Worst instrument I ever owned for stability was a Strat copy... just look at it sideways and it needed tuning twice. Actually play it and you were in 'alternative' tuning territory almost immediately. Don't miss that piece of firewood :-)