my 96 sxi has 120psi in both cyls. i bought it many years ago with a SBT replacement motor in it. it runs fine but seems like it has no low end power.. when i look in spark plug hole i see a 1.00 written on top of piston, does that mean its a 1mm overbore so i should buy 81mm pistons? should i have machine shop hone cyls before puttin new pistons in? is 120psi low for a stock SBT motor? what pistons should i buy, Wiseco? thanks