As far as power goes you should start with the basics, a good intake, chip, and exhaust. As as for a 5-speed, switching out an automatic for a manual is no walk in the park, I mean the getreg 5-speed bell houseing does bolt right up to the engine, but theres alot of other shit that goes along with a MT; slave cylander, master cylander, the clutch, you probly need to get a driveshaft out of a 5-speed also. Although if your planning on doing serious modifications to the engine in the future, I'd suggest looking into a ZF 5-speed from a 328, they can take alot more tourqe. If you don't want to spend the money paying someone to do the manual conversion, or time and effort doing it yourself, an automatic trans chip from dinan can help.