[kapsz28]

So I have been told that back pressure is not a good thing on naturally aspirated motors and you should try to reduce all the back pressure as possible, then tune your car, and then you should get the best performance. Right?

I have a Saturn Astra with a 1.8l ecotech motor pushing 138hp. I don't plan on modifying the engine at all, so what would be the best route for reducing the back pressure to get the best performance?

Should I throw on an exhaust with 3-4" piping, and then have it properly tuned on a dyno?

I am really interested in how back pressure and engine performance works. So if someone can enlighten me, that would be great.