cbrakllr88

I just installed my 5" auto gage autometer tach. I didnt go with the tach adapter just spliced into the engine speed signal through the PCM. It works just fine but the RPMs are reading 800 lower than the stock tach. it says in the instuctions that 8cyl. dont need any calib ration adjustment. They said 8 cylinders have 4 pulse. But someone was telling me that LS1's has 2 pulse. so That means i have to cut wires i the tach(directions say not to unless 6 or 4 cylinder appl.) what do I do? Any help is greatly appreciated.