can anybody tell me what a resonator is and what it does? does it have any pros and cons? My main concern is how its going to make my exhaust sound. i'm looking the deepest throaty sound possible on my 99 si

 

I'm told that if you take out the resonator, your exhaust will sound like a tin can. (you've heard them before, you know what I'm talking about)

Mr^Man

 

resonators quite your exhaust down, think of it like a 2nd muffler almost. IMO i don't really think a car could sound worse with a resonator, but a glass pack or something might sound a little odd [&:] Magnaflow is generally whats recommend on here, i've got a Maganflow res and i love it. The longer you get it, the more it muffles the sound as well. I've got a 22" one and it does the trick.

 

i've got my Greddy EVO2 exhaust and love it. i bought it just for the simple reason that it's known for being quiet. but now w/ the upgraded engine (and i'm sure the new header will make it a good bit louder) i'll be replacing my High Flow Cat with a HKS High Flow resonator within the next month or so.
you'll see about the same performance drop as you would from puting on a cat rather than a test pipe. and that is very common misunderstood part. most people are under the impression that it's a huge HP difference, no. in an issue of import tuner i had a year or so back they did a test with all 3 (stock cat, high flow cat and test pipe) on a 320whp STI i believe. going from a stock cat - high flow cat = 1whp. from a high flow cat to a test pipe = 2whp. so it really doesnt' make much difference.
good luck.