Agree with magnetic tray (easy to put lug nuts and other bolts in).

I always carry a spare impact wrench battery.

I like redundant sockets for high-use applications. I have three 19mm deep sockets. One for the impact wrench, one for the breaker bar and one for the torque wrench.

 

The reason I posted the essentials of my box were that well, I have never been wronged. But also on my last car, the RSX Type-S with Supercharger, my tool box had everything needed to take the SC off. Also I have had electronic engineers over here for a really amazing alarm install, and well he brought some stuff, but those tools still allow you to install electronics into a car, include solder, soldering iron and heat shrink wrap.

But the biggest issue I have seen when under the car is 2 sets of 6 point sockets and ratchets. Craftsman or better, when you break the cheap ebay junk you will know what I mean, don't even bother with that step. Up above I twisted out a torque wrench when I tried to torque the wheels back on, on my RSX and the stupid POS broke. Think about how hard that is to drive down after you are working on your car to pick a part up, thats assuming you have another car!!!

 

To clear up the diff bolt question... it has been my experience that the drain bolt is a 24/23 and the fill bolt has been a 24/23. I put slashes because on my car it was one way and on my friends they were switched. One bolt had a magnet on it so I put that as the drain bolt. My friend's was the other way so we switched them on his car. I don't remember if the bolt with the magnet is the 24 or 23. Hope that makes sense.

And yes 1mm will make a difference. It either won't fit or you'll strip it.

 

I believe the fact that it is 24mm for the drain bolt and 23mm for the fill bolt is the biggest flaw of the S2000.

Anyway, you could get a several hundred piece craftsman set if you think you need it. I chose not to because 1) I wouldn't use 80% of those tools anyway (don't need SAE tools at all so there's 50% right there), 2 - trunk space is at a premium when you're packing an S2000 for a track weekend. My tool bag is pretty small and contains everything I've ever needed in the past 6+ years of ownership. There are things I do bring when going to the track that don't come along on weekend drives or autox's (jack, jack stands, wheel chocks, impact wrench).