i dont have any input on mmr or modular performance (actually ordered an mmr 4.75 liter long block for a customer 2 weeks ago), but i will say after seeing a dss super pro bullet 347 long block that was a 9.5:1 NA motor kick 2 "forged" connecting rods through the block when it was 1000 miles old, and their absolute lack of caring. i think id keep my distance from them. and upon further inspection after it came apart i found rings that weren't staggered in 3 cylinders, the connecting rods look like cheap chinese metal, and really nothing special, no coated bearings or anything, all in all, i wasnt impressed for the $