on my car when it had sport 700 turbos. I had the late model heads and manifolds on the car with 740cc injectors; I killed the heads road racing the car due to oil starvation. I did not have another set of late model heads, but I did have a set of early heads all ready to go with the same larger valves and port work as the killed heads, so I installed them. The tune was the same, as well as the power output on the dyno with both sets of heads. I could not find any differences in the way the car ran in any way.