I actually used 4 grounds, one on the back of the trans, one on the front of the trans, one on the back of the head & one on the IM. Make sure the ground from the engine harness (near injectors) makes good contact with the engine. Tech - K-Series Engine Ground
I used a thread chaser bolt to clean the threads of the holes on the chassis really good & a wire brush wheel to clean the threads on the bolts that ground the wires.
The link shows the ground on the valve cover just like I did. But I will add another to the trans and move the ground in the front block to the rear of the block near the timing chain cover and header. I did have two grounds to the same spot on the chassis (one off the back of the IM and one off the front of the block)which I didn't think would be a problem but maybe it is.....