For the most part. The s2k started to break away from that, as is the new Civic Si. The S2k still has pretty quiet exhaust, but if you notice, it is almost impossible to make more than 2 hp out of them by doing full exhaust. Taht proves how much tuning went into the breathing systems in those s2k. The new civic's are also breaking away from honda's normal quiet=better, but that is also due to the fact that they are trying to attract younger buyers with the Si's.

 

It all depends on if you plan on going tubo or not!!! If so then just wait it is not worth it to waste $$$$ on somthing that you will have to cange later anyways, but if you want to just hear a nice sound and feel no differance then do it. As for the MPG of couse it makes it better but not to a huge extent. The whole you can get 20 hp out of this intake is b/s you can get it if you change alot of thing that deal with the intake like the throttle body with a spacer then there you have it 20 hp easy! and you will notice it then

 

The new Si does have alot of intake noise when the i-VTEC kicks in at 6 grand. The exhaust isn't that loud, but is louder than the EX, I am not sure how loud it is since I haven't had someone drive it by me yet. Right now I am trying deside what intake go with and see what it sounds like then.