I have been thinking for a little while about getting a Mivec 4G92 engine for my Australian Lancer (US Mirage) to get a little more oomph, my mechanic friend suggested that rather than doing that to just get the diff ratio changed (custom job) for more acceleration and change 5th gear so it doesn't rev too high on the highway.

Just want to get some feedback as to whether this is feasable and any problems I might encounter.

 

To change the diff ratio in a front wheel drive you have to change the input shaft and diff ring gear. I dont know anyone who sells something like that for your trans.

 

I would recommend doing a Mivec conversion, the engine is good for 130kw and can be tweaked higher. Bolts straight in, one of the easiest conversions. Do not worry about what your friend told you as the Lancer engine is not designed for that. The Mivec is a true race engine and is well woth the money. Also the cheapest conversion for the Lancer