ok i drive a 06 zx3 5 spd... and my car didnt come with a tach.. i can still drive it ok but it would b more appealing to me and alil bit more fun to drive without tryin to geuss exactly how far i can go to redline with out acctually bouncin it off... so im gunna purchase one with a tach but does nebody now the deal with installing it? can i do it myself or do i need to have the dealer do it to get the milage correct... or is the miliage stored in the cars computers? and how would i go about to do the swap(where r the screw bolts torexs? thank-you.. please let me know asap before i purchase it.