Two main problems arise when talking 318 performance, Velocity and Compression, for most it's simple add a 4bbl 600/650 and a cam 205 to 215 maybe headers, a stall and deeper gears would be nice and a good tune and if want a bit more power do something about the heads. Then the Velocity and Compression Police come along and make it a jumble of confusion for the OP on what to do and make it sound impossible to squeeze an extra 50-100hp out of a mild 318.