If you realy want to gain HP on your SOHC a Ford Probe exhaust manifold will bolt right up. If you found a good Probe turbo and manifold for cheap you might be able to make it work. You will have to find a way to clock the turbo to clear the motor mounts but it might work. Other than that you can try all the old reliable stuff. a good open air filter like a K&N, a 2 1/4" exhaust with a quality turbo muffler like a MagnaFlow or Flow Master, and convert your clutch fan to an electric. All this might be good for a 15 to 25 HP, not quite the 50 but every little bit helps. No body makes kit for any of this but if you are handy most of this stuff is posted here on the Wire.

Dennis