I'd have to go back and look at see what the max bore they were using then. I know WC was a longer stroke with a smaller bore. IIRC at that time max bore was 4.600-4.605 and I think WC said they were at 4.550 so you are taking fly poop and pepper numbers. They were losing more with th 4 speed.
I was at Woodburn when there was some 5 speed testing going on. Even with the engine/chassis/clutch they were using for the Nationals, they were quicker with the 5 speed. They just unhooked the 5th gear lever in Seattle. Everyone and their mother said the 5 speed wouldn't be any faster.
