Dyno numbers are all over the map; relativities on the same dyno are all that really matter. It was clearly doing more than 400hp at the crank on a hot engine and, as with any dyno less airflow than it would have on the street. With all the elctronics the SRT has I'm not sure how reliable any dyno would be as an absolute number. If you don't find any durability issues, it sounds like the 185 may be the way to go when my warranty expires.

Most mfr ECU tunes on boosted vehicles are set rich to limit detonation and presumably get less powertrain warranty claims. My EVO has the same issues with the factory tune. That's how they always magically can pull another 25hp out of the stock ECU settings after 5 minutes on the dyno. I know slight differences in the exhaust and cam are cited for the 20 or so hp difference between the SLK32 AMG and the SRT-6 but I really do suspect that Chrysler just chickened out on the waranty potential and tuned it richer to build in more safety margin. A more enlightened approach is to lean it out for most of the rev range and simply dump more fuel the last 800rpm.

Good luck with it and please post how she holds up!