I dont know what kind of weather you usally get there but that should play a key role in picking a box.
Mild steel (ie cheaper systems) will rust very quickly in wet weather (living by the coast or in your case constant rain)
If you are interested in looking for a system that will last for sometime look into a stainless steel system as this will stand up to the weather more than the cheaper mild steel units.
So while the look of the tips count alot the construction of the unit itself is just as important as well. So that you dont have to keep on replacing that affordable muffler very often that the price is the same as a high quality one