ANYONE FOUND A WAY TOO InCREASE HORSE POWER ON A 1980  --  1984 4CYL SUBARU MOTOR  PROPANE KIT MAYBE  ??  ??  ??

Propane has less energy per charge than gasoline.

EA81 or EA82 engine?
 

Anything you do will reduce the reliability.   Cost a lot.  Take a lot of time.  To get small gains.  Parts are rare, and getting scarcer.

Install a 2.2EJ engine.  A lot of work, but real gains in power and reliability in the engine.  And parts are still available.  40% HP increase may not be good for the rest of the drive line, but many have done it.

 

Hmmmm no EA82 in that era so be EA81

I wonder if you are getting at the Diesel/propane idea of adding propane to intake air in times of need?

Propane nominally only had 80% the energy of 80's leaded fuel...so to get much same power you use more fuel.And increase ignition timing. Propane is a bit more torque rather than sharp crisp power come on and generally not like to come to the party at high revs not care too much about economy

There are many tricks to find if you search. Nothing is ever cheap

basic stuff, weber carb and maybe some exhaust work.  not much actual gain in HP but its in much more usefull places. 

low horsepower to start means low horsepower at end in general.  as stated EJ swap is the only real chance for power.