If you ask that mech to do the modification for you, you are going to be in a world of pain. Injector duty cycle has to be kept around 60%. Anytime it goes above 80%, it will start to overheat and jam. You can't run your injector duty cycle near 100% without anything exploding from your engine.

However, piggybacks do not tune the ECU at all. It just changes the signal going into the ECU and tricks the ECU with a different reading. I don't call that tuning as you can't change the parameters of the original ECU mapping. Tuning capabilities are limited as it still relies on the original parameter of the ECU.

So, if the original ECU for NA runs on MAP, it most probably does not have maps for positive boost pressure and the piggyback will not be sufficient to correct this. Only and aftermarket standalone ECU can.

Correct but there is one problem. Without an aftermarket ECU, you will have problems controlling the injector while you are driving below 0 psi boost. The stock ECU cannot cope with the larger capacity and I won't be surprised to even see black smoke coming out even while you are idling. Even aftermarket ECUs will not be able to resolve this issue.

I guess I didn't make myself clear too. I wasn't talking about a BOT KITs with piggyback and separate wiring loom and injectors like those sold by RPW in Australia for Proton. Those cost more than a standalone ECU on some kits. Usually piggybacks come into mind as a simple piggyback controllers without external kits. Those will not make it for BOTs.

Yes, there are very extensive piggybacks but I won't call them piggybacks anymore as you'd need to purchase a whole new set of wiring looms and sensors if the original ECU does have it. These are called conversion kits that are very popular overseas but not here.

Unfortunately, for the local scene, it is the other way around. Labour is cheap and engine conversions are the norm. Overseas, labour is charged per hour and engine conversions cost more. Here, it cost more to tune an ECU than to do an engine conversion. I got the quote to retune my ECU for RM3000 (without dyno as they get the maps from the internet too). What a rip off. I do it myself for less than RM400 (to get the cable). Mappings I can get from the internet and I find hundreds of cars with the exact same mods as mine and just use their tried and tested mappings.

Piggybacks (and conversion kits) suffer the same problem here. Cost too much and hence it is not popular. However, with the 4G93T engine fading into the history books and new Protons can't use them easily, the only option for most people now is to go BOT. Do hope that one day we do see the BOT kits hear other than the one offered by Proton a long time ago.

I don't need piggyback. My ECU is based on open ecu programming that can be fully flashed with all the necessary mappings.

Your boost controller depends on the turbines internal/external wastegate. Boost controllers let you adjust the boost above but not below the original spring tension. So if the stock boost is 0.7, you can't use a boost controller to set it below that. You'd have to adjust the wastegate or get one that is set lower.