Any info on 1781cc Spi. 8v Engines?

[Mk3golfer]

I have a Mk3 golf with a 1.8 spi engine, Its the adz engine, and as far as i understand lacks the Mpi the gti's have... anyone have any info on what i should be doing to look after the engine and anyone have any experience with them? It runs a treat and i havent had any problems so far... also does anyone know what i can do to get some more power out of it? obviously its not going to mind blowing i just want it to have a little bit more grunt... it already has a custom pipe and manifold!