Since you want n/a and some suggest the new Coyote engine, I figured in addition I'd mention the old (01'ish era, S62) M5 5.0 v-8 with double VANOS, itb's, etc. 400hp 369ft/lbs stock. They and are on ebay time to time with ecu/harness (sometimes with 6 speed) for a reasonable cost or car-part.com