90+bhp at the wheels sounds about right. Transmission losses are around 8-10%.
111bhp is what is stated by Proton. I've got lots of magazines from the 1990s showing a 1.6 wira/satria having that figure quoted. Those versions from UK with the catlytic converters are worse, getting about 97-99bhp at the flywheel.
Using a performance filter and exhaust system means that the car ISN'T stock anymore. Hence, the guy who said that the 1.6 makes 120bhp in stock form is confused. If anyone wanted to know how 120-125bhp goes, try the single cam 1.8 wira. of course, there is a difference in torque which the 1.6 does not have.
To convert to a 1.8mivec, you need a 1.8 block, then the mivec head with its inlet manifold, exhaust manifold, wiring, ecu, distributors etc. You may as well buy:
1. the 1.8 block (make sure you got correct papers for registration with jpj)
2. a 1.6 mivec half cut so that you dont get a headache sourcing for the parts required.
its gonna cost you a bomb, not worth it as if for example you owned a 1997 wira 1.6, trade in value is eg. rm15,000.00 and the parts and installation cost in total close to rm7,000.00. of course you could resell the 1.6 block and body parts, but still, it's too tedious. might as well sell the 1.6, buy a 1.8 twin cam wira from 1996-1997 which would cost about 15-20k and then plonk in a mivec head. That's why I haven't bothered with it after years of ownership.
regards