FW headers:
618tq@4100
639tq@4500
638hp@6100
616hp@6800
2-2 1/8 x 4 dyno headers:
518tq@4100
637tq@4800
673hp@6300
665hp@6800
The crossover point was 4700rpm.
Both were 567hp@4700, then the dyno headers just pulled away.
FW headers were 100tq better at 4100.
