i'd stay away from them, i had the amr one which was supposed to add 4 degrees of timing. it seemed to run good or so i thought until i put the stock cdi back on and installed an adjustable timing plate, set it to +4 and it ran ten times better.
so i'd keep the stocker and install the chariot adjustable plate and set it to +4 you'll be saving yourself some money too
stock cdi's are made by denso so they're real good quality not like the chinese junk on ebay