My Swiftech mini reservoir makes no gurgling noise once the system is bled and all the air is out.
The alternative if you don't want a reservoir is a t-peice but I would advise making a long pipe up to the top of your case, make a hole in your case and put a filling plug in the top (google them, you can get them). This has the advantage that you have a nice long pipe so a reasonable amount of extra coolant plus it makes it very easy to fill/top up.
Pedant mode: on
It's actually called a fillport
Pedant mode: off
