i know bout the 2 inch piping that eat oil... but for normal drive with 60 bucks oil no speeding.. i can drive onli 200+ km onli.. wow...
my ex car which was a satria 1.6 did 400km with 60 bucks of petrol. which was an auto, and converted to manual transmission. 2" piping, straight flow some more.
and my e3 in my putra can easily do 240km with 60 bucks.
i advise that 2" isn't suitable for the 1.6 auto based on my own experience. but you can save it for your future manual.
go ahead and convert your tranny to a manual. common prices range from 1200-1400. any lower than that with acceptable workmanship, consider yourself lucky. all the best.