David, what are you going to use for collector size and length on the headers??? I keep waiting for someone to plunk down the big bucks for a set of merge collectors to see if they are actually as good as the claims of the people who make them!!!!! I've used the Flowmaster 4 into 2 into 1 collectors, they were good for 12 horse on the chassis dyno....unfortunately there was enough other variable on the two pulls that I can't really say all the gain was from the collectors..... Torque gain from 3500 to 7000 was significant, too!!!!!