got back from chassis dyno from this guys shop...
http://www.youtube.com/watch?v=_FdF0wgTikM
looks like my homemade jobbers made best of 625 hp@7000 rpms.best open headers run was 650@7000. thats on roughly a 800 hp 572.
on a 260 hit of nitrous it made 854@7000 thru mufflers with air fuel ratio ranging from 10 to 10.5 to 1
i realize i need to relieve pressure and not to dead head regulators even though my pump has a return right off it to fuel cell. when fuel pump is on with 6 pounds flowing fuel, not flowing its like 12 pounds thus telling with the rich condition on spray it wants a return line.......
final answer, 3% power loss with home made mufflers...not bad for 3" id 4" od bullet mufflers with half inch holes swiss cheesed in the 3" pipe.