help 5kt timing retard problem

[Jay <j-yr-be@snet.net>]

My 5kt motor (MC) cannot seem to find a timing setting it likes.
 Anything above 4psi of boost the engine plays with the timing back and
 forth but i have never heard knock.  There are no codes in the
computer.  I run mobil 93 allways.  New fuel filter and intake boot.
5psi feels really weak, barely like a turbo car because of the timing.  
	Where do i find the $20 bosh platinum plugs?  I don't mean the $1.80
ones.
                                         Thanks, Jay