1. You can use it with a Schrick Vgi or standard manifold. 256, 248 or stock cams would work well an s/c. Cams are more for mid range torque than peak power. 2. Stage 1 (6 psi) should give 250-270 hp, 230-240 lb ft torque. Perhaps a bit more with vgi, cams and a remap. 3. They are pretty reliable. I've covered 30k miles with no issues.