Cat C18 acerts are 1150hp, they burn 85 gph at 80% load. I would say your Detroits on their best day are putting out 1000hp and probably even less now. That combined with some weight savings from the Cats, you'd see a 4-5 knot increase. But CAT has nothing really between the c 18 and C32. So you're either a 6 cylinder or massive 12 cylinder. Hp is HP and it takes X amount of fuel to make X amount of HP on a modern diesel. You have enough fuel, and I forget what 10v2000's burn, I ran one set at 1400hp or somewhere around there, and I think they were 120GPH for the pair at 80% load. I didn't like the way they ran, they were in a 64' Hatteras MY, you'd get to around 1950rpms, the one turbo would cut out the boat would fall on it's face and drop to 1850rpms, then the other turbo would cut in and quickly start accelerating again, it was odd. Like being on a bucking bronco. I ran the boat from WPB,FL to St. Michaels, MD probably 5 years ago. They are not a very common engine at all and in that HP range C32's are found in most all SF in MY's till you get to the 16v2000 range, also Viking put them in a SF in the beginning and found they were way overpropped based on their initial calculations of what prop they should be running in that hull and came to the conclusion they didn't make the HP they claimed. What HP MTU's did they use to get 30 knots?