Calvin,
GSR/EVO ECU wiring does NOT detect boost. Mitsubishi all run on MAF sensor not MAP sensor... which means they detect air flow and not boost (pressure). =p So there's no difference. My turbo kit worked fine on my 4G91 wiring and ECU, plus I was running high boost... all you need is good piggy back =p
skylee,
Registering a GSR is LEGAL. Only 2.0 is illegal. There is no law that limits the percentage of displacement. The only difference is you go through a different process of legal documents for below and above 20% cc upgrade.
JPJ is taking advantage of us by controlling the upgrade from 1.3 --> 1.8... thats why we pay them a price for it. Its not illegal, but they won't lulus your transplant unless u give them some insentive. =p
I wouldn't recommend a you to bore your 4G91 block, coz' it ain't strong, and what more you're turbo kitting it.
There could be a lot of decisions to make. Whether you want to go with a 4G92 block with supercharger/GSR pistons. Or maybe a GSR block. Or maybe place order for custom JE/Wiseco forged pistons (should cost bout 2k+ for a set of 4) and retain your block. But if you're gonna spend big, would it be more worth it to transplant a GSR straight and start modding from there? There's no "best choice", because diff people have diff opinions.
My opinion?
Drop in a GSR straight. Because don't forget if u're starting off from a 4G91 and slowly buying 1 part by 1 part and spend more and more and more, GSR turbo kit, GSR wiring, GSR ECU, GSR intake manifold, GSR this, GSR that... in the end what do you get after spending shitloads? A stock GSR. =p
And then u go test car with a GSR and u notice something... a stock GSR is more powerful, more reliable, and gives a better fuel consumption than yours. =p
My friend's stock Satria GSR put in s/steel intercooler piping with VR4 i/c and 2.5" exhaust boosting at 1 bar with e-manage dynoed kicking 200hp on the wheels, can give over 450km mixed driving on a full tank petrol. =p
On the other hand... someone else I know turbo kitted his Satria GTi, changing everything to a GSR (except maintained the 4G93p block), can never out run a stock GSR and can hardly touch 300km on full tank petrol... not to mention visits the workshop monthly to fix this and that.