Even my Kia dealership says stay away from piggybacks. Iv asked a lot about tuning and mods. They recommend tune by ECU for the forte and tune on spare if money's not an issue for warranty work.
Sales guys I used has an optima with lap3 and loves it but also says he's heard nothing but bad thing with lap3 on fortes.
Do what ever you want of course. But I'd just get the tune on a spare ECU and spend the money once.. And enjoy the added power.
Fully agree. Yes the performance gain from both a piggyback or a tune is very significant but there is little to no physical hardware being used as to other performance items in that same price range. They are mostly software related, not saying that doesn't take hardwork and long hours to perfect, but by no means should cost an arm and a leg just to change the way the ecu works. That's my rant and that why I will not tune yet because I can't bring myself to spend that type of money on just a file.
Build your own piggyback.
It may all be possible with a raspberrypi.
I've done similar stuff on older cars with just switches pots and resistors.
Lap3 is only looking at 2 sensors and has settings for 3 different octane levels with either pots or jumpers to switch resistors.
It wouldn't be too difficult to build something that applied different resistances at given rpms and throttle positions.
What would be easiest is just add a toggle switch with 1 set resistor.
I won't be doing this but it's basically what lap3 has done. The last option i listed would be really cheap.