Absofriggin'lutely.
Kobolds are my little Chosen. I would not even dare send a group of PCs under 6th level after them without feeling like they are getting slaughtered, or I'm not playing the Kobolds right.
Yes, yes, sweet yes. Kobolds have a 10 Int, which is par with a Human. They are seen as cannon fodder, they are physically weak, and they have a bad habit of earning the wrath of anyone with a decent sword and spell. This means, they need to Prepare.
Yes, small tunnels. But then there are going to be traps set for adventurers. Kobolds don't need torches. This means flammable things hidden in the ceilings. Tunnels that have an elevated roof to fit a medium sized individual, spesificly to set traps their head would trigger (Can you say a tripwire caught on your helmet, firing a crossbow bolt between your eyes?). Murder holes, arrow slits, pungi pits to catch those on their hands and knees. Poisonous creatures (Snakes, wasps, spiders, etc) housed in jars and thrown. Imagine a few half dozen trained weasels sicked on a party, or a dire badger, while they are in this restricted little hole? Or, imagine the horror of a Kobold nest that breeds and 'trains' stirges?
Heck, I imagine Kobolds could learn how to construct catapults that fire around corners (Dwarves have!). And then there is magic. How about a Control Flame targetted at a Torch? Or a bucket of oil? Grease makes a perfect addition to sloping tunnels, especially if you have a Slow coming online right behind it. Lightning bolts in those tiny tunnels will no doubt cause restricted Ref saves. Tanglefoot bags, Thunderstones, and poisons, poisons, poisons. Sorcerors who may focus on Counterspelling to deal with pesky mages who may Fireball the nest, or crossbowmen who focus on disrupting spells.
But that is just in a Kobold's nest, where you don't want to fight them. What about out in the open? You better believe they are going to have traps set up at ambush points. Pit traps either in the road or along the side. Bridges? They are going to have tripwires, caltrops, and greases on them. Invisible kobolds in spiderholes waiting. A kobold in Melee is a Dead kobold. Always have somewhere you can excape to. And of course, a hired help (the assistance of an ogre or bugbear for help can always be good).
Of course, Kobolds are going to be making deals with anything nearby, not just raiding it stupidly. They are going to offer magic and a cut of profits to intelligent monsters near by. Why, they may offer a trade agreement to a town. 'We don't raid you or any of your travellers into the town, you send us tribute once a month. This can be oil, supplies, food, so on. It will save lives, and effort of paying adventurers to kill us. Think of your wallets. We'll keep monster populations down, or out of your hair. With your assistance and tribute.'
I can very much see Kobolds as Socalist. Not fully, but they regard the Nest as nearly as important as their own survival. Everyone gets a small 'share' of the take, but the majority goes to the Nest's funds. And those who do exceptionally well get rewarded.
And then you have your kobolds who are exceptionally powerful. Wizards, sorcerors, priests, rogues. Cleric/Barbarians (When you get Divine Power) are... scary.
A kobold is only limited to how you limit them.
Make Them Proud.