A lot of the difference is the way the v8 will run vs the I6.
My Ford vs my Dodge, stock, the Ford is considerably quicker, but the Dodge has more balls while towing. The Ford does 'OK', but the mileage is way off. Depending on which program he has, he could be anywhere from 350rwhp/650rwtq, to 450rwhp/750rwtq.
i would like to see that dyno page for that!! i have seen many 6. 0no's dyno and never in the mid 400 without drugs! most that are stock only push 280 or so to the rear and the "stock" with programmers only make it to the mid to upper 300's... ... . i think the ones in the 400's. . they go boom! lol