Hey, let me be the first one to say welcome! I don't know about having a gas flowed head, but the Si is a capable engine, and port/polish and a cat-back exhaust definitely make a difference in the power you feel!
It takes a lot less engine size and power to make these cars go fast, that's why they're gaining popularity with so many people. However, most people still opt for swapping out the original Si motor in favor of something that offers a higher power base, like a SOHC Vtec, DOHC ZC, or B16A. They all swap in more or less easily, and I guarantee you'll get a hankering for more power soon enough! So, enjoy your Si and get ready to want more!! Like a wise man once said, modding your car makes heroin addiction seem like a vague desire for something salty!! Happy Driving!
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