Hi,
I have still have this car

but due to Turkish otomotive rules I can't swap 2.0L engine to 1.6L.
If I have 1.8 engine I could swap 2.0L.

anyway, I still do some thing to this engine and I decided to do CAI system, full exhaust system(with out cat) and headers.
for exhaust system I gonna use straight tube but for the efficient performance which size tube I have to use?? 51mm or ??
for the headers which one is the best for street drive 4-2-1 or 4-1??
this car is not going to be track day car.
also you could give me some idea to make my car.
thank you.