Well heres what I plan on doing just to make sure it's to my benefit. I pieced together a D series Turbo kit. Everything I need I have. Well my motor has 193K on it so a turbo would kill it in no time probably. So I decided to rebuild my motor. Well this is my only car so I don't need it in the shop awhile. I then decided to buy another D series block to build up. I am going with 8.5:1 comp forged pistons, Eagle H beam rods, crane stage 3 turbo cam, titanium valves, and adjustable cam gear. (Any other suggestions to what I might need?) After I get my block built I am going to redue my head so and put it on for little down time. My question is should I go with another D16 block or will the D15 block work just as well? I am going to be running low boost daily, but when I take it to the track probably 20 psi. I wan't the best block possible. Also are our blocks sleeved from the factory?