Hi again. my advice is, go with the engine absolutely stock. Is a great engine as it is, for sport and training duties it will give you years of very nice flying...
Remember thats is much better to have a very nice stock engine than a ruined by a bad reworking.
If you need a more powerful engine, i suggest you to buy another engine with a bigger displacement (OS 46 LA, ST 51, OS 40/46 SF-S among many others...)
good luck Maurice