Ok, I got EG 4door, for DD, and it will stay as DD so, I can get z6 head, rebuilded for ~350$, then was thinking of some 4-2-1 header, got an 60mm exhaust, then get in tuned in Compression Calculator by ZealAutowerks i did this setup with d15b2 stock block + unmiled stock z6 head, 2layer HG...