T/A lt1

I really don't use the factory tach while racing b/c I have a MSD shiftlite and just use that to shift but I noticed while on the transbrake my tach will bounce around like I am having some sort of wiring problem. If I put the T-brake on go WOT the tach jumps around from 4000-4200 eractically and I am also having issues with a high rpm miss. So I am thinking this is not a coincidence. Anyone els have anything similar happen? LMK Later Clint