Depends on your budget, cheapest way to gain 25bhp is fit a 1.7 Puma lump. If you want to keep the 1.6, full exhaust, set of Shawspeed SS4 cams, remap and if you want to be safe, some HD bottom end bolts, should see around 150bhp on a healthy engine.
Jenvey ITB's cost big bucks, and you'll have to run aftermarket management (OMEX 600 is the popular choice) but you won't gain a massive amount of power for the money. Lovely noise though!