You could get a tach. :P
As for what speeds.. *shrug* someone else will have to answer or you could check your manual if you have one.
[Edit]Nevermind, the manual has speeds for "best compromise between performance and fuel economy", not all out rod throwing crazy[/edit]
In the event that you do get a tach; in another thread Gumby seems to say that it was 6500RPM (said that his rear mounted tach matched the stock v6 one) https://www.thirdgen.org/forums/post...60-post27.html