73 mach1, lots of room for speculation here, for me its all about whos dyno, who is operating the dyno and how much loss from engine to tires.
I have a similar 408 with very similar camshaft but closed chambers and 10.6 static and 8.1 dynamic.
on software 1 am anywhere from 500 to 520 hp. at the crank, its all in the translation.
where did you have emi/rfi on your sniper?, I have installed a few of these units on gm cars and have not encountered any of this as of yet, i did install the secret emi tape and redundant grounds before installs and thats what I am crediting my sucess to.