I have a 99 civic si and im considering getting full custom header back 2.5 inch exhaust to the stock muffler. i just want my car to be quiet as possible but still perform. With the stock muffler on there will i be losing power?

 

Yes, your exhaust system is only as strong as the weakest component. If you are wanting to stay with something stock, i would suggest you get an ITR axelback. It flows quite a bit better than other stock honda exhausts, and is very quiet as well.