i put some headers on my civic if i put a full cat back exhaust system wil i notice an big change and noise?

Answer 1

you will not notice any different in power but a little different sound . you have to change the exhaust pipe and muffler in order to feel more horsepowers

Answer 2

Judging from your current add-ons, i'll assume you already have a performance intake. Fact is that you will feel a significant difference in both sound and horsepower. To maximize the hp gain you should map you car on a dyno run to properly tune your cars performance. Unless you do this, you'll never unleash the true potential of your dollar spent. Good luck, have fun.