The lower octane you can find in europe is 95 and on that my chip is tuned on
that we call it unleaded

Now we also have the v-power as lets say Shell cals it that claims to have 98 octane ( and ofcorse other companies call it different names )

and the V-power Racing that claims to be even more...

Just to have a comparison
for the simple unleaded 95 we pay 1.2 - 1.26 euros per Liter

so every little fuel economy counts..
I belive that the ideal - maximum that you can do for a N/A sportage
is
programm ( yes it works for what is worth for a N/A engine )
a good header + freeflowcat + Plumbing of the exauste
a BMC barel type filter
electric fan
a little Shaving of the head to increase compresion a little bit ( but then with the risk of damaging the valves if you break a timing belt)together with a little porting and maching

allthat combined in a good engine I belive can get you to the area of 160 hp compared the the 130 stock since - dont forget that - we have an UNDERPOWERED version of the same mazda engine that with leaded fuel 10.something compresion different program ( solved that!!) different cams had some 180Hp...