2.5'' or 2.0'' Piping for 1500cc

[hondacivic856]

Hi, i hope someone can help me to decide which is the proper yet gaining power.
Meron akong 1995 Honda Civic Lx which means carb type pero na-convert na namin sa efi.

Head - ZC non-vtec 99 model came from Japan
Block - Ph15 PM3 Pistons  :applause:

Sa madaling salita, High Compression yung oto pero stock port, Stock internals No head modifications. 

Iniisip ko what is the proper piping, lets say 4-2-1 Headers
ano sukat ng piping ang dapat ko gamitin? Yung hindi power lost. Sabi nila kasi 2.5'' Piping then 24'' Scuv ang iniisip ko naman hindi kaya maging "Sungaw"

I hope you can help me.

[downtown]

anything from 2 to 2.25-inch, nothing more.