tach and electronic dissy advice

[ta63-1uzze]

hay all, so having a bit of a brain fart with this. looking for some electronics people to shove me in the right direction please 

i have upgraded to an electronic dissy in my mini, its bloody awesome, no more points yay. but the down side is my tachometer now doesn't work. well it moves ever so slightly but no where near reading rev's 

so in my mind i am thinking i have removed the ballast resistor thus changing the was 9 volts to the coil to the now full supply voltage of 14.2v . so i was thinking if i put a resistor going to ground in between the gauge and the negative terminal of the coil where the tachometer gets its signal from .  that i could successfully burn up a few volts making the signal to the tachometer back into the correct scale of 9 volts ?  now in my mind if i put it is series it would draw more current through the gauge and that would cook it, so if i just splice it in before the gauge and i used the correct resistor i could burn up some of them extra pixies making my signal back down to 9volts ??

 

so all this is just an idea, i dont know if i am on the right track with this. if i am wrong and there is no easy fix i will change my plan of attack , ill go and destroy and new aftermarket rev counter and make a mini/aftermarket mash up of sorts. i would in however like to try and get my head around this electric pixie stuff cause i do find it rather fascinating . and i do quite like these little battles

 

thanks in advance . chur 

[tortron]

if you  have an rvi type tach they don't like to work with the electronic dissys, an rvc will work happily

 

I found this about the RVI type

[ta63-1uzze]

oh that was fast response, i have a clubman gt 3 gauge dash cluster . is there an easy way to tell what it is ?  im not familiar with rvi or rvc at all.