head speed question

[astra 8vt]

can a silly head speed cause tail problems ?

ive just counted my pinion and it was a 13 tooth and i thought it was an 11 and i just worked my head speed out to a rather large amount

done the 11.1 x motor x tooth / 150 and the total was .....3703 !! it screams it nuts off !! but does shift

going on the above with the 11 tooth on works out at 3133


would i be better dropping it to the 11 tooth

what would be the best head speed for a 450 ?


thanks

jay